Reapply "Support for precise stepping in functions compiled before debugging was started (step 2)"

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index c6fa55435653808ea690e5b8918aeaf25240239a..84cf8dff641c92b7af89e6939908b07379218da9 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2982,6 +2982,21 @@ void Code::set_has_debug_break_slots(bool value) {
 }
 
 
+bool Code::is_compiled_optimizable() {
+  ASSERT(kind() == FUNCTION);
+  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
+  return FullCodeFlagsIsCompiledOptimizable::decode(flags);
+}
+
+
+void Code::set_compiled_optimizable(bool value) {
+  ASSERT(kind() == FUNCTION);
+  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
+  flags = FullCodeFlagsIsCompiledOptimizable::update(flags, value);
+  WRITE_BYTE_FIELD(this, kFullCodeFlags, flags);
+}
+
+
 int Code::allow_osr_at_loop_nesting_level() {
   ASSERT(kind() == FUNCTION);
   return READ_BYTE_FIELD(this, kAllowOSRAtLoopNestingLevelOffset);