Version 4.7.57

Disallow Object.observe calls on access-checked objects (Chromium issue 531891).

Implement V8 extras utils object (issue 4276).

ES6: Array.prototype.slice and friends should use ToLength instead of ToUint32 (issue 3087).

Avoid excessive data copying for ExternalStreamingStream::SetBookmark (issue 4422).

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.57@{#1}
Cr-Branched-From: a6e00c6-refs/heads/master@{#30785}

Version 4.7.56

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.56@{#1}
Cr-Branched-From: f5bec4b-refs/heads/master@{#30755}

Version 4.7.55

Fix spread operator in ArrayLiterals when nested in other literals (issue 4417).

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.55@{#1}
Cr-Branched-From: f44efd6-refs/heads/master@{#30754}

Version 4.7.54

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.54@{#1}
Cr-Branched-From: 1e00bb5-refs/heads/master@{#30737}

Version 4.7.53

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.53@{#1}
Cr-Branched-From: 32dffda-refs/heads/master@{#30723}

Version 4.7.52

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.52@{#1}
Cr-Branched-From: 43a0403-refs/heads/master@{#30717}

Version 4.6.85.17 (cherry-pick)

Merged 1a8c38c
Merged 206f12a

[heap] Fix recursive GCs caused by adjusting externally allocated memory

[heap] Properly decrement amount of externally allocated memory

BUG=chromium:526244
LOG=N
[email protected]

Review URL: https://codereview.chromium.org/1344823002 .

Cr-Commit-Position: refs/branch-heads/4.6@{v8#20}
Cr-Branched-From: 24d34a8-refs/heads/4.6.85@{#1}
Cr-Branched-From: 8f44118-refs/heads/master@{#30256}

Version 4.7.51

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.51@{#1}
Cr-Branched-From: eadfd66-refs/heads/master@{#30706}

Version 4.7.50

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.50@{#1}
Cr-Branched-From: d8eade4-refs/heads/master@{#30704}

Version 4.7.49

Performance and stability improvements on all platforms.

Cr-Commit-Position: refs/heads/4.7.49@{#1}
Cr-Branched-From: ea8cfa9-refs/heads/master@{#30703}