This enables other emdedders to reuse parts of the standalone embedder
implementation without depending too much on the implementations details.
As part of the change we also remove a dependency from DartUtils on
IsolateData - by removing dart:_builtin library caching. Lookup
of this library does not seem to be on hot path anymore in Kernel world.
Change-Id: Ia35b28886121828fad7a96f00bcbceff75e00ae8
Reviewed-on: https://dart-review.googlesource.com/64848
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
Vyacheslav Egorov