Update V8 to r7427: Initial merge by git

As required by WebKit r82507

Change-Id: I7ae83ef3f689356043b4929255b7c1dd31d8c5df
diff --git a/include/v8-testing.h b/include/v8-testing.h
index 4db30a4..245f74d 100644
--- a/include/v8-testing.h
+++ b/include/v8-testing.h
@@ -87,6 +87,11 @@
    * should be between 0 and one less than the result from GetStressRuns()
    */
   static void PrepareStressRun(int run);
+
+  /**
+   * Force deoptimization of all functions.
+   */
+  static void DeoptimizeAll();
 };