Update V8 to version 4.3.57.2 (cherry-pick).

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/d125e47c..b8c26baf

Please follow these instructions for assigning/CC'ing issues:
https://code.google.com/p/v8-wiki/wiki/TriagingIssues

TBR=hablich@chromium.org,machenbach@chromium.org,yangguo@chromium.org,vogelheim@chromium.org

Review URL: https://codereview.chromium.org/1030773004

Cr-Commit-Position: refs/heads/master@{#322379}

DEPS

@@ -47,7 +47,7 @@ vars = {
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.
   'v8_branch': 'trunk',
-  'v8_revision': 'd125e47ce6264d95ca07588a88b630007be18291',
+  'v8_revision': 'b8c26bafb12fc4b0966d7314c20d337072ddaabd',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling WebRTC
   # and V8 without interference from each other.