[es6] stage sticky regexps and RegExp.prototype.flags (issue 4342).

[Crankshaft] Don't do HMathFloorOfDiv optimization for kUint32 values (issue 4507).

Fix user options for fractional digits in Intl.NumberFormatter (Chromium issue 544122).

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.8.134@{#1}
Cr-Branched-From: 9a594e783add26ecabc74f611d7e31b9a549ee65-refs/heads/master@{#31482}