This change adds support for allowing for imports of unsupported
platform-specific libraries when the
`--include-unsupported-platform-library-stubs` flag is provided to the
CFE.
This flag sets the `includeUnsupportedPlatformLibraryStubs` property in
`TargetFlags`, which `Target`s can use to conditionally return different
`DartLibrarySupport` objects with different supported/unsupported
library sets.
A `checkForUnsupportedDartColonImports` function has been added to
`Target` that uses the value of `dartLibrarySupport` to determine if
there's any unsupported library imports. This function is called after
the various transformation operations provided by the `Target`
implementation, meaning the import of an unsupported library specified
in `dartLibrarySupport` will now result in a compilation error (this
includes `dart:mirrors` imports for VM targets when mirrors are
disabled, which was previously handled by the VM itself).
Related to https://github.com/dart-lang/sdk/issues/62125
TEST=Tests added / modified
Change-Id: Ife819b2e1a6d28f67d80aab6701cd23a1724aa4d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/465760
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>
Ben Konyi
b5e60be49d