Roll src/third_party/re2/src/ 9a227bed7..749d64c35 (3 commits)

https://chromium.googlesource.com/external/github.com/google/re2.git/+log/9a227bed7a0f..749d64c35e09

$ git log 9a227bed7..749d64c35 --date=short --no-merges --format='%ad %ae %s'
2018-11-05 junyer Optimise the check for large substrings.
2018-11-05 junyer Fix the check for large substrings.
2018-10-31 junyer Improve the "MATCHING WITH SUBSTRING EXTRACTION" comment.

Created with:
  roll-dep src/third_party/re2/src

R=mmoroz@chromium.org

Bug: 902131
Change-Id: Ic281b472f8c68e64c33d026859ed8e3429c015f5
Reviewed-on: https://chromium-review.googlesource.com/c/1319341Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Max Moroz <mmoroz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605712}

DEPS

@@ -1065,7 +1065,7 @@ deps = {
   },
 
   'src/third_party/re2/src':
-    Var('chromium_git') + '/external/github.com/google/re2.git' + '@' + '9a227bed7a0fde418a94c967ef92d4a1fbe5e47f',
+    Var('chromium_git') + '/external/github.com/google/re2.git' + '@' + '749d64c35e09849045303c3de4e9955597b75b53',
 
   'src/third_party/r8': {
       'packages': [