Fix preamble/d8.js currentScript for v8 6.9
Fix preamble/d8.js currentScript for v8 6.9

Change-Id: I3783c51dc4f26ca21c368840758f7acf34f710b7
Reviewed-on: https://dart-review.googlesource.com/c/78865
Reviewed-by: Sigmund Cherem <beaea8fd7d2a56555046ba4f362c8a93e3938576@google.com>

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