Update V8 to r6101 as required by WebKit r74534

Change-Id: I7f84af8dd732f11898fd644b2c2b1538914cb78d
diff --git a/src/api.h b/src/api.h
index e36160c..d07d75b 100644
--- a/src/api.h
+++ b/src/api.h
@@ -31,6 +31,8 @@
 #include "apiutils.h"
 #include "factory.h"
 
+#include "../include/v8-testing.h"
+
 namespace v8 {
 
 // Constants used in the implementation of the API.  The most natural thing
@@ -489,6 +491,18 @@
          (!blocks_.is_empty() && prev_limit != NULL));
 }
 
+
+class Testing {
+ public:
+  static v8::Testing::StressType stress_type() { return stress_type_; }
+  static void set_stress_type(v8::Testing::StressType stress_type) {
+    stress_type_ = stress_type;
+  }
+
+ private:
+  static v8::Testing::StressType stress_type_;
+};
+
 } }  // namespace v8::internal
 
 #endif  // V8_API_H_