e6b983cef Build legacy web dart sdk (flutter/engine#11360) (#39023)

git@github.com:flutter/engine.git/compare/ccf5d619b58a...e6b983cefe2a

git log ccf5d619b58a..e6b983cefe2a --no-merges --oneline
2019-08-22 jonahwilliams@google.com Build legacy web dart sdk (flutter/engine#11360)

The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff (liyuqian@google.com), and stop
the roller if necessary.

bin/internal/engine.version

-ccf5d619b58a956303cdd408c7c1ba2c2cf35cbd
+e6b983cefe2a14c0653e48990f3e35da6089d04d