Roll re2 db20d46..ae9cb49.

https://chromium.googlesource.com/external/github.com/google/re2.git/+log/db20d46..ae9cb49

TBR=tfarina@chromium.org, thakis@chromium.org
BUG=700259

Review-Url: https://codereview.chromium.org/2743883003
Cr-Commit-Position: refs/heads/master@{#456088}

DEPS

@@ -303,7 +303,7 @@ deps = {
     Var('chromium_git') + '/external/github.com/cisco/openh264' + '@' + '0fd88df93c5dcaf858c57eb7892bd27763f0f0ac',
 
   'src/third_party/re2/src':
-    Var('chromium_git') + '/external/github.com/google/re2.git' + '@' + 'db20d46c05900a12539225fe800dd860b14e0061',
+    Var('chromium_git') + '/external/github.com/google/re2.git' + '@' + 'ae9cb49a2e2ba95de4f0c6ec5a8afd039996d2c7',
 
   # Used for building libFuzzers (only supports Linux).
   'src/third_party/libFuzzer/src':