Update V8 to version 6.2.118.1 (cherry-pick).

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/fca6d756..7b7658d8

Please follow these instructions for assigning/CC'ing issues:
https://github.com/v8/v8/wiki/Triaging%20issues

Please close rolling in case of a roll revert:
https://v8-roll.appspot.com/
This only works with a Google account.

NOTRY=true
because of strange bot errors.

CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel
TBR=machenbach@chromium.org, ulan@chromium.org

Change-Id: I94dffc086c933ef1f31276fd8a6d052251f8aa2e
Reviewed-on: https://chromium-review.googlesource.com/596973
Commit-Queue: Michael Hablich <hablich@chromium.org>
Reviewed-by: Michael Hablich <hablich@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491347}

DEPS

@@ -44,7 +44,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.
-  'v8_revision': 'fca6d7563e4fad451e9bff85e96f6490596cc9dd',
+  'v8_revision': '7b7658d8c800e8a42d2c0b5bc9bbe63155a69a22',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.