[vm/build] Pass predefined environment variables to compile_platform.
[vm/build] Pass predefined environment variables to compile_platform.

This is needed for correct frontend constant evaluation of [type].fromEnvironment() expressions.

Fixes https://github.com/dart-lang/sdk/issues/36307.

Change-Id: I0332bdcc432148ce2338c6591b18387d835add6e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/98434
Reviewed-by: Siva Annamalai <2e618a8cbd7bb6b3d4409061ae407d692a098546@google.com>
Commit-Queue: Alexander Aprelev <dfb74c35a357c2059971a4bf7fe26b6a7c18085d@google.com>

dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk