Fix spec violations related to regexp.lastIndex

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 5cf2d44cb50f13a3a956142fc705466d8d5c2f66..fd622f29f7c6d8639a67939c7bff74d910a85bb8 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -1790,9 +1790,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_RegExpInitializeObject) {
         JSRegExp::kIgnoreCaseFieldIndex, ignoreCase, SKIP_WRITE_BARRIER);
     regexp->InObjectPropertyAtPut(
         JSRegExp::kMultilineFieldIndex, multiline, SKIP_WRITE_BARRIER);
-    regexp->InObjectPropertyAtPut(JSRegExp::kLastIndexFieldIndex,
-                                  Smi::FromInt(0),
-                                  SKIP_WRITE_BARRIER);  // It's a Smi.
+    regexp->ResetLastIndex();
     return regexp;
   }
 
@@ -2904,7 +2902,10 @@ MUST_USE_RESULT static MaybeObject* StringReplaceAtomRegExpWithString(
       isolate, *subject, pattern, &indices, 0xffffffff, zone);
 
   int matches = indices.length();
-  if (matches == 0) return *subject;
+  if (matches == 0) {
+    pattern_regexp->ResetLastIndex();
+    return *subject;
+  }
 
   // Detect integer overflow.
   int64_t result_len_64 =
@@ -3004,6 +3005,7 @@ MUST_USE_RESULT static MaybeObject* StringReplaceRegExpWithString(
   int32_t* current_match = global_cache.FetchNext();
   if (current_match == NULL) {
     if (global_cache.HasException()) return Failure::Exception();
+    regexp->ResetLastIndex();
     return *subject;
   }
 
@@ -3102,6 +3104,7 @@ MUST_USE_RESULT static MaybeObject* StringReplaceRegExpWithEmptyString(
   int32_t* current_match = global_cache.FetchNext();
   if (current_match == NULL) {
     if (global_cache.HasException()) return Failure::Exception();
+    regexp->ResetLastIndex();
     return *subject;
   }