Combine DEBUG_BREAK and DEBUG_PREPARE_STEP_IN into one IC stub kind DEBUG_STUB, encoding DEBUG_BREA…

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 658214a22996ef6186761787a3a55f85e6c60de0..cb0c87cc567730675b0c3b46acd805a771b1973d 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -3418,14 +3418,13 @@ InlineCacheState Code::ic_state() {
   // a call to code object has been replaced with a debug break call.
   ASSERT(is_inline_cache_stub() ||
          result == UNINITIALIZED ||
-         result == DEBUG_BREAK ||
-         result == DEBUG_PREPARE_STEP_IN);
+         result == DEBUG_STUB);
   return result;
 }
 
 
 Code::ExtraICState Code::extra_ic_state() {
-  ASSERT(is_inline_cache_stub());
+  ASSERT(is_inline_cache_stub() || ic_state() == DEBUG_STUB);
   return ExtractExtraICStateFromFlags(flags());
 }