- Removes the load port functionality from the service isolate, this was
used to load sources in Dart 1 and is pretty much dead code in Dart 2
- Moves resolution of URIs and Package URI (based on package map) to the
individual isolates instead of sending a request to the service isolate
- Setups the package map lazily as it is needed only if resolveURI is
called in Dart code, it is not needed for loading/compiling sources
(this is now done in the front end).
- Removed Dart_ServiceWaitForLoadPort() methods from the Dart C API as
it is not used anywhere.
Change-Id: I6c3704bc431bdcd49bf074eb58bee1ed492ccccb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/129742
Commit-Queue: Siva Annamalai <asiva@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
- Removed ResolveDependenciesAsFilePaths functionality as the loader
does not track any dependencies (this is now provided by the kernel
isolate)
- Removed ResolveAsFilePath functionality from the loader class
- Removed some left over code related to deferred loading
Change-Id: Ic1b1a79b07020bb7082e9efb7544b73931290faf
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/122220
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Siva Annamalai <asiva@google.com>
This reverts commit 3d14b75f97.
An Isolate Group (IG) is a collection of isolates which were spawned from the
same source. This allows the VM to:
* have a guarantee that all isolates within one IG can safely exchange
structured objects (currently we rely on embedder for this
guarantee)
* hot-reload all isolates together (currently we only reload one
isolate, leaving same-source isolates in inconsistent state)
* make a shared heap for all isolates from the same IG, which paves
the way for faster communication and sharing of immutable objects.
All isolates within one IG will share the same IsolateGroupSource.
**Embedder changes**
This change makes breaking embedder API changes to support this new
concept of Isolate Groups: The existing isolate lifecycle callbacks
given to Dart_Initialize will become Isolate Group lifecycle callbacks.
A new callback `initialize_isolate` callback will be added which can
initialize a new isolate within an existing IG.
Existing embedders can be updated by performing the following renames
Dart_CreateIsolate -> Dart_CreateIsolateGroup
Dart_IsolateCreateCallback -> Dart_IsolateGroupCreateCallback
Dart_IsolateCleanupCallback -> Dart_IsolateGroupShutdownCallback
Dart_CreateIsolateFromKernel -> Dart_CreateIsolateGroupFromKernel
Dart_CurrentIsolateData -> Dart_CurrentIsolateGroupData
Dart_IsolateData -> Dart_IsolateGroupData
Dart_GetNativeIsolateData -> Dart_GetNativeIsolateGroupData
Dart_InitializeParams.create -> Dart_InitializeParams.create_group
Dart_InitializeParams.cleanup -> Dart_InitializeParams.shutdown_group
Dart_InitializeParams.shutdown -> Dart_InitializeParams.shutdown_isolate
By default `Isolate.spawn` will cause the creation of a new IG.
Though an embedder can opt-into supporting multiple isolates within one IG by
providing a callback to the newly added `Dart_InitializeParams.initialize_isolate`.
The responsibility of this new callback is to initialize an existing
isolate (which was setup by re-using source code from the spawning
isolate - i.e. the one which used `Isolate.spawn`) by setting native
resolvers, initializing global state, etc.
Issue https://github.com/dart-lang/sdk/issues/36648
Issue https://github.com/dart-lang/sdk/issues/36097
Original review: https://dart-review.googlesource.com/c/sdk/+/105241
Difference to original review:
* Give each isolate it's own [Loader] (for now)
* Sort classes during initialization for spawned isolates if app-jit is used (to match main isolate)
* Fix IsolateData memory leak if isolate startup fails
Difference to first reland(Patchset 2):
* Fix typo where memory was freed twice.
Change-Id: Ib1c83fe83b629cd50ae6af90ee99fdd44da882d4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/108367
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
This reverts commit 67ab3be10d.
Reason for revert: Causes non-deterministic failures on front-end bots on Windows with "Isolate creation failed" error. See https://logs.chromium.org/logs/dart/buildbucket/cr-buildbucket.appspot.com/8909292129328681248/+/steps/unit_tests/0/stdout
Original change's description:
> Reland "[vm/concurrency] Introduce concept of Isolate Groups"
>
> An Isolate Group (IG) is a collection of isolates which were spawned from the
> same source. This allows the VM to:
>
> * have a guarantee that all isolates within one IG can safely exchange
> structured objects (currently we rely on embedder for this
> guarantee)
>
> * hot-reload all isolates together (currently we only reload one
> isolate, leaving same-source isolates in inconsistent state)
>
> * make a shared heap for all isolates from the same IG, which paves
> the way for faster communication and sharing of immutable objects.
>
> All isolates within one IG will share the same IsolateGroupSource.
>
> **Embedder changes**
>
> This change makes breaking embedder API changes to support this new
> concept of Isolate Groups: The existing isolate lifecycle callbacks
> given to Dart_Initialize will become Isolate Group lifecycle callbacks.
> A new callback `initialize_isolate` callback will be added which can
> initialize a new isolate within an existing IG.
>
> Existing embedders can be updated by performing the following renames
>
> Dart_CreateIsolate -> Dart_CreateIsolateGroup
> Dart_IsolateCreateCallback -> Dart_IsolateGroupCreateCallback
> Dart_IsolateCleanupCallback -> Dart_IsolateGroupShutdownCallback
> Dart_CreateIsolateFromKernel -> Dart_CreateIsolateGroupFromKernel
> Dart_CurrentIsolateData -> Dart_CurrentIsolateGroupData
> Dart_IsolateData -> Dart_IsolateGroupData
> Dart_GetNativeIsolateData -> Dart_GetNativeIsolateGroupData
> Dart_InitializeParams.create -> Dart_InitializeParams.create_group
> Dart_InitializeParams.cleanup -> Dart_InitializeParams.shutdown_group
> Dart_InitializeParams.shutdown -> Dart_InitializeParams.shutdown_isolate
>
> By default `Isolate.spawn` will cause the creation of a new IG.
>
> Though an embedder can opt-into supporting multiple isolates within one IG by
> providing a callback to the newly added `Dart_InitializeParams.initialize_isolate`.
> The responsibility of this new callback is to initialize an existing
> isolate (which was setup by re-using source code from the spawning
> isolate - i.e. the one which used `Isolate.spawn`) by setting native
> resolvers, initializing global state, etc.
>
> Issue https://github.com/dart-lang/sdk/issues/36648
> Issue https://github.com/dart-lang/sdk/issues/36097
>
> Original review: https://dart-review.googlesource.com/c/sdk/+/105241
>
> Difference to original review:
>
> * Give each isolate it's own [Loader] (for now)
> * Sort classes during initialization for spawned isolates if app-jit is used (to match main isolate)
> * Fix IsolateData memory leak if isolate startup fails
>
> Change-Id: I98277d3d10fe275aa9b8a16b6bdd446bbea0b100
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107506
> Commit-Queue: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
TBR=kustermann@google.com,aam@google.com,rmacnak@google.com
# Not skipping CQ checks because original CL landed > 1 day ago.
Change-Id: Ia4e0f4f9fc317499d3570a371c5bdf9aed799e77
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/108101
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Vyacheslav Egorov <vegorov@google.com>
An Isolate Group (IG) is a collection of isolates which were spawned from the
same source. This allows the VM to:
* have a guarantee that all isolates within one IG can safely exchange
structured objects (currently we rely on embedder for this
guarantee)
* hot-reload all isolates together (currently we only reload one
isolate, leaving same-source isolates in inconsistent state)
* make a shared heap for all isolates from the same IG, which paves
the way for faster communication and sharing of immutable objects.
All isolates within one IG will share the same IsolateGroupSource.
**Embedder changes**
This change makes breaking embedder API changes to support this new
concept of Isolate Groups: The existing isolate lifecycle callbacks
given to Dart_Initialize will become Isolate Group lifecycle callbacks.
A new callback `initialize_isolate` callback will be added which can
initialize a new isolate within an existing IG.
Existing embedders can be updated by performing the following renames
Dart_CreateIsolate -> Dart_CreateIsolateGroup
Dart_IsolateCreateCallback -> Dart_IsolateGroupCreateCallback
Dart_IsolateCleanupCallback -> Dart_IsolateGroupShutdownCallback
Dart_CreateIsolateFromKernel -> Dart_CreateIsolateGroupFromKernel
Dart_CurrentIsolateData -> Dart_CurrentIsolateGroupData
Dart_IsolateData -> Dart_IsolateGroupData
Dart_GetNativeIsolateData -> Dart_GetNativeIsolateGroupData
Dart_InitializeParams.create -> Dart_InitializeParams.create_group
Dart_InitializeParams.cleanup -> Dart_InitializeParams.shutdown_group
Dart_InitializeParams.shutdown -> Dart_InitializeParams.shutdown_isolate
By default `Isolate.spawn` will cause the creation of a new IG.
Though an embedder can opt-into supporting multiple isolates within one IG by
providing a callback to the newly added `Dart_InitializeParams.initialize_isolate`.
The responsibility of this new callback is to initialize an existing
isolate (which was setup by re-using source code from the spawning
isolate - i.e. the one which used `Isolate.spawn`) by setting native
resolvers, initializing global state, etc.
Issue https://github.com/dart-lang/sdk/issues/36648
Issue https://github.com/dart-lang/sdk/issues/36097
Original review: https://dart-review.googlesource.com/c/sdk/+/105241
Difference to original review:
* Give each isolate it's own [Loader] (for now)
* Sort classes during initialization for spawned isolates if app-jit is used (to match main isolate)
* Fix IsolateData memory leak if isolate startup fails
Change-Id: I98277d3d10fe275aa9b8a16b6bdd446bbea0b100
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107506
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
This reverts commit b75057b687.
Reason for revert: Caused some failures on app-jit builders
Original change's description:
> [vm/concurrency] Introduce concept of Isolate Groups
>
> An Isolate Group (IG) is a collection of isolates which were spawned from the
> same source. This allows the VM to:
>
> * have a guarantee that all isolates within one IG can safely exchange
> structured objects (currently we rely on embedder for this
> guarantee)
>
> * hot-reload all isolates together (currently we only reload one
> isolate, leaving same-source isolates in inconsistent state)
>
> * make a shared heap for all isolates from the same IG, which paves
> the way for faster communication and sharing of immutable objects.
>
> All isolates within one IG will share the same IsolateGroupSource.
>
> **Embedder changes**
>
> This change makes breaking embedder API changes to support this new
> concept of Isolate Groups: The existing isolate lifecycle callbacks
> given to Dart_Initialize will become Isolate Group lifecycle callbacks.
> A new callback `initialize_isolate` callback will be added which can
> initialize a new isolate within an existing IG.
>
> Existing embedders can be updated by performing the following renames
>
> Dart_CreateIsolate -> Dart_CreateIsolateGroup
> Dart_IsolateCreateCallback -> Dart_IsolateGroupCreateCallback
> Dart_IsolateCleanupCallback -> Dart_IsolateGroupShutdownCallback
> Dart_CreateIsolateFromKernel -> Dart_CreateIsolateGroupFromKernel
> Dart_CurrentIsolateData -> Dart_CurrentIsolateGroupData
> Dart_IsolateData -> Dart_IsolateGroupData
> Dart_GetNativeIsolateData -> Dart_GetNativeIsolateGroupData
> Dart_InitializeParams.create -> Dart_InitializeParams.create_group
> Dart_InitializeParams.cleanup -> Dart_InitializeParams.shutdown_group
> Dart_InitializeParams.shutdown -> Dart_InitializeParams.shutdown_isolate
>
> By default `Isolate.spawn` will cause the creation of a new IG.
>
> Though an embedder can opt-into supporting multiple isolates within one IG by
> providing a callback to the newly added `Dart_InitializeParams.initialize_isolate`.
> The responsibility of this new callback is to initialize an existing
> isolate (which was setup by re-using source code from the spawning
> isolate - i.e. the one which used `Isolate.spawn`) by setting native
> resolvers, initializing global state, etc.
>
> Issue https://github.com/dart-lang/sdk/issues/36648
> Issue https://github.com/dart-lang/sdk/issues/36097
>
> Change-Id: I82437ac017ca33018d45e02f353b0672db155f6a
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/105241
> Commit-Queue: Martin Kustermann <kustermann@google.com>
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Reviewed-by: Alexander Aprelev <aam@google.com>
TBR=kustermann@google.com,aam@google.com,rmacnak@google.com
Change-Id: Ibd90992a01d61188f27b445c21532e0c46f996ea
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/107405
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
An Isolate Group (IG) is a collection of isolates which were spawned from the
same source. This allows the VM to:
* have a guarantee that all isolates within one IG can safely exchange
structured objects (currently we rely on embedder for this
guarantee)
* hot-reload all isolates together (currently we only reload one
isolate, leaving same-source isolates in inconsistent state)
* make a shared heap for all isolates from the same IG, which paves
the way for faster communication and sharing of immutable objects.
All isolates within one IG will share the same IsolateGroupSource.
**Embedder changes**
This change makes breaking embedder API changes to support this new
concept of Isolate Groups: The existing isolate lifecycle callbacks
given to Dart_Initialize will become Isolate Group lifecycle callbacks.
A new callback `initialize_isolate` callback will be added which can
initialize a new isolate within an existing IG.
Existing embedders can be updated by performing the following renames
Dart_CreateIsolate -> Dart_CreateIsolateGroup
Dart_IsolateCreateCallback -> Dart_IsolateGroupCreateCallback
Dart_IsolateCleanupCallback -> Dart_IsolateGroupShutdownCallback
Dart_CreateIsolateFromKernel -> Dart_CreateIsolateGroupFromKernel
Dart_CurrentIsolateData -> Dart_CurrentIsolateGroupData
Dart_IsolateData -> Dart_IsolateGroupData
Dart_GetNativeIsolateData -> Dart_GetNativeIsolateGroupData
Dart_InitializeParams.create -> Dart_InitializeParams.create_group
Dart_InitializeParams.cleanup -> Dart_InitializeParams.shutdown_group
Dart_InitializeParams.shutdown -> Dart_InitializeParams.shutdown_isolate
By default `Isolate.spawn` will cause the creation of a new IG.
Though an embedder can opt-into supporting multiple isolates within one IG by
providing a callback to the newly added `Dart_InitializeParams.initialize_isolate`.
The responsibility of this new callback is to initialize an existing
isolate (which was setup by re-using source code from the spawning
isolate - i.e. the one which used `Isolate.spawn`) by setting native
resolvers, initializing global state, etc.
Issue https://github.com/dart-lang/sdk/issues/36648
Issue https://github.com/dart-lang/sdk/issues/36097
Change-Id: I82437ac017ca33018d45e02f353b0672db155f6a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/105241
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
In many cases, the Mutexes and Monitors have to be marked "mutable"
because they're used to synchronize const accessor methods.
Small text segment improvement for Product builds:
$ size dart.{arm,x64}.{before,after}
text data bss dec hex filename
19726069 409960 392332 20528361 1393ce9 dart.arm.before
19725525 409960 392332 20527817 1393ac9 dart.arm.after
22576021 600376 1782824 24959221 17cd8f5 dart.x64.before
22574821 600376 1782824 24958021 17cd445 dart.x64.after
Change-Id: I68f5cd5ad452044df8bfebd160910496036a3e6b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/101745
Commit-Queue: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Change some static_libraries to source_sets to make ODR violations link-time errors.
This is needed to enable (stop suppressing) -fvisibility=hidden in Fuchsia product builds.
Change-Id: I699cec8d4b516beab9cebf9db0a522a7ff99e004
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/99822
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
- Remove all code that generates the corelib and dart:io library sources into C++ arrays and link them into dart_bootstrap
- Remove the executable dart_bootstrap and all uses of it
- Remove bootstrap_nolib.cc and builtin_nocore.cc
- Remove the Dart 1 code in core lib bootstrap path
Change-Id: Ifd33496204285a08b42fe09e39428e7a92b416b6
Reviewed-on: https://dart-review.googlesource.com/c/77241
Commit-Queue: Siva Annamalai <asiva@google.com>
Reviewed-by: Zach Anderson <zra@google.com>
We need to use the actual file URL of the importing library to find the extension library,
such as "file:///library/lib.dart" rather than the package URL (like "package:library/lib.dart").
Change-Id: I32a36f7a67321f356c9af34d1a458aeb122d0c24
Reviewed-on: https://dart-review.googlesource.com/71167
Commit-Queue: Samir Jindel <sjindel@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Tested with imports through current directory, VM binary directory,
and LD_LIBRARY_PATH. This also restores the Dart 1 behavior of not supporting
relative extension paths.
Change-Id: I090bf8592fef74d4ccde40e6f550baa84c98e3bc
Reviewed-on: https://dart-review.googlesource.com/69162
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Samir Jindel <sjindel@google.com>
- Forward only kImportTag requests to DFE. This restores the current handling of a kScriptTag request when loading the kernel isolate in the simulators.
- Mark dynamic_load_test as failing in the reload stress tests (reload fails to preserve library identity).
Change-Id: Ibe6f0a3505b99736a38d566abf3b2151505d7a7e
Reviewed-on: https://dart-review.googlesource.com/56706
Reviewed-by: Siva Annamalai <asiva@google.com>
This reverts commit ad4cfa0260.
Reason for revert: Assertion failures on DBC
Original change's description:
> [mirrors] Add IsolateMirror.loadUri.
>
> This allows a programmer to dynamically load code into an isolate. The closest existing API is Isolate.spawnUri, but communication with the dynamically loaded code in that case is limited to asynchronous message passing of JSON-like objects.
>
> Change-Id: Icb23e9dacfb0035622c119f11d4e0f892ba2ccd1
> Reviewed-on: https://dart-review.googlesource.com/45363
> Reviewed-by: Zach Anderson <zra@google.com>
TBR=rmacnak@google.com,zra@google.com,asiva@google.com,kmillikin@google.com
Change-Id: I80669188b9f40b3b527e8e268ade0d0d514a8753
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/56640
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
This allows a programmer to dynamically load code into an isolate. The closest existing API is Isolate.spawnUri, but communication with the dynamically loaded code in that case is limited to asynchronous message passing of JSON-like objects.
Change-Id: Icb23e9dacfb0035622c119f11d4e0f892ba2ccd1
Reviewed-on: https://dart-review.googlesource.com/45363
Reviewed-by: Zach Anderson <zra@google.com>
Update status for simulators, which the test harness invokes with DIL files instead of source files.
Change-Id: I8444ad7e17a0a71a1ce3c0021487397baa1c3e65
Reviewed-on: https://dart-review.googlesource.com/54622
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
- Enabled incremental compiler in the dart frontend for the command-line VM
- Added method to update in-memory file system with in-memory sources provided by tests
Change-Id: Ica26b7235383185dbb6b4b41064193d432dfcba0
Reviewed-on: https://dart-review.googlesource.com/36126
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
This change, and the code introduced, is probably not going to be required
once the platform kernel file is linked into the executable.
Change-Id: I24a837c3a633a625145cf90ff83d3e51b3d23eb6
Reviewed-on: https://dart-review.googlesource.com/36720
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Siva Chandra <sivachandra@google.com>
The isolate creation callback flow was using DFE::kernel_file_specified()
to decide whether to load kernel program or not. However, since this flag
is not isolate specific, it was causing problems in the case where a dill
file was passed as the main dart program; the other isolates, even if
they were loading a snapshot, were looking for a kernel program.
This change was originally submitted as
"Make the decision, on whether to start the kernel isolate, liberal." It
was reverted due to failures on simdbc bots. This change is another
attempt which fixes those failures.
Change-Id: I096445faf470e77ab8f7cc810082891dcede5b60
Reviewed-on: https://dart-review.googlesource.com/36125
Commit-Queue: Siva Chandra <sivachandra@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Use depfiles for the SDK's application snapshots.
Add check that we don't try to create a script snapshot after loading from an app snapshot.
Bug: TO-596
Change-Id: Ib4209c3062dbe0f3c37b8f65e5a50ca64544a39b
Reviewed-on: https://dart-review.googlesource.com/26043
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Zach Anderson <zra@google.com>
After https://dart-review.googlesource.com/c/sdk/+/7588 we ended up with two crypto.dart files in the core prebuilt libraries(io and _http), which caused problem with coverage tool that relied on the fact that script uris can uniquely identify files. https://github.com/dart-lang/coverage/issues/194 was filed to handle non-unique uris.
This CL ensures that core builtin libraries URIs stays unique by prefixing them with 'dart:' library prefix. This makes core builtin libraries scripts have names similarly structured to script names for other core libraries.
Bug:
Change-Id: I79960f4f24e6e958836df866365355584c28df27
Reviewed-on: https://dart-review.googlesource.com/11140
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
This is needed to support cases where memory with kernel binary was
allocated outside of Dart VM(for example, in Flutter Engine) has to be
released using appropriate mechanism too.
Bug:
Change-Id: I863db9e5a33469ba8fb5c1f8789c6498ddfbb385
Reviewed-on: https://dart-review.googlesource.com/5121
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
2. Adjust the Dart front end to not require a 'main' method when the in memory filesystem is used, this allows execution of VM unit tests which all do not necessarily have a 'main' method (integrated CL from siggi)
3. Change kernel reader to not look for a 'main' methos when Dart_LoadKernel is called.
4. Change Dart_LoadScript to also support loading of dart programs when Dart front end is used
R=aam@google.com, sigmund@google.com
Review-Url: https://codereview.chromium.org/2948273002 .
2. Read the platform dill file at startup not for every isolate creation
3. Store the memory representation of kernel program in isolate data so that it is deleted when the isolate is shutdown
R=aam@google.com
Review-Url: https://codereview.chromium.org/2927493002 .
Only reload packages map when we are actually doing the isolate reload.
Snapshotting creates and destroys and loader object every time it loads a dart
file - which means kInitLoader is on the hot path and we should avoid rereading
packages map.
R=asiva@google.com, rmacnak@google.com
Review-Url: https://codereview.chromium.org/2901093002 .
Ryan Macnak