This is important as we will soon add support for compiling the sdk as a
module and we would like to only compile it once when running a suite of
tests.
+ also enable caching in the dart2js pipeline test.
Change-Id: Ic9043f868123164f3ab425ba73f7428416b05fc0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103485
Commit-Queue: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>