RegExp: Add support for the ES6-proposed sticky flag

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 8dbe46490318ed6c0f68452383824fd88e9e9245..b265a682b0128f031f9d211ff906ef24b8aee7dd 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -9699,6 +9699,16 @@ void HOptimizedGraphBuilder::GenerateTypedArrayMaxSizeInHeap(
 }
 
 
+void HOptimizedGraphBuilder::GenerateHarmonyRegExps(
+    CallRuntime* expr) {
+  DCHECK(expr->arguments()->length() == 0);
+  HValue* value = FLAG_harmony_regexps
+      ? graph()->GetConstantTrue()
+      : graph()->GetConstantFalse();
+  return ast_context()->ReturnValue(value);
+}
+
+
 void HOptimizedGraphBuilder::GenerateArrayBufferGetByteLength(
     CallRuntime* expr) {
   DCHECK(expr->arguments()->length() == 1);