Port irregexp bytecode compiler and interpreter from V8 r24065.

runtime/vm/intrinsifier_x64.cc

Index: runtime/vm/intrinsifier_x64.cc
diff --git a/runtime/vm/intrinsifier_x64.cc b/runtime/vm/intrinsifier_x64.cc
index ca458ac82ca861a55e8df96c010257d2e6e1bd24..96fe7bca00e0cb229675496543ce48cf21153768 100644
--- a/runtime/vm/intrinsifier_x64.cc
+++ b/runtime/vm/intrinsifier_x64.cc
@@ -17,6 +17,8 @@
 
 namespace dart {
 
+DECLARE_FLAG(bool, interpret_irregexp);
+
 // When entering intrinsics code:
 // RBX: IC Data
 // R10: Arguments descriptor
@@ -1936,6 +1938,8 @@ void Intrinsifier::TwoByteString_equality(Assembler* assembler) {
 
 
 void Intrinsifier::JSRegExp_ExecuteMatch(Assembler* assembler) {
+  if (FLAG_interpret_irregexp) return;
+
   static const intptr_t kRegExpParamOffset = 3 * kWordSize;
   static const intptr_t kStringParamOffset = 2 * kWordSize;
   // start_index smi is located at offset 1.