Update V8 to version 4.5.39.

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/607696b0..f4760990

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/1156273009

Cr-Commit-Position: refs/heads/master@{#333116}

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': '607696b0517e49769c04ebf1cca0d3148e40e81c',
+  'v8_revision': 'f4760990c6a0c4a4514a10629a005ee9bc3fc1a1',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling WebRTC
   # and V8 without interference from each other.