Correct semantics for numerically indexed stores to typed arrays.

src/lookup.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/bootstrapper.h"
 #include "src/deoptimizer.h"
 #include "src/lookup.h"
 #include "src/lookup-inl.h"
@@ skipping 291 matching lines @@
       property_dictionary->ValueAtPut(dictionary_entry(), *value);
     }
   } else if (property_details_.type() == v8::internal::FIELD) {
     holder->WriteToField(descriptor_number(), *value);
   } else {
     DCHECK_EQ(v8::internal::CONSTANT, property_details_.type());
   }
 }
 
 
+bool LookupIterator::IsSpecialNumericIndex() const {
+  if (GetStoreTarget()->IsJSTypedArray() && name()->IsString()) {
+    Handle<String> name_string = Handle<String>::cast(name());
+    if (name_string->length() > 0) {
+      double d =
+          StringToDouble(isolate()->unicode_cache(), *name_string, NO_FLAGS);
+      if (!std::isnan(d)) {
+        Factory* factory = isolate()->factory();
+        Handle<Object> num = factory->NewNumber(d);
+        Handle<String> roundtrip_string = factory->NumberToString(num);
+        if (String::Equals(name_string, roundtrip_string)) return true;
+      }
+    }
+  }
+  return false;
+}
+
+
 void LookupIterator::InternalizeName() {
   if (name_->IsUniqueName()) return;
   name_ = factory()->InternalizeString(Handle<String>::cast(name_));
 }
 } }  // namespace v8::internal