Allow to neuter array buffer twice in tests.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 1caaff05f8e0fc61018a6bd245f8c41ceef75d7b..e091c8fb5e3152a1cc39c2b9d89aa0aa2ceb353f 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -911,6 +911,10 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_ArrayBufferIsView) {
 RUNTIME_FUNCTION(MaybeObject*, Runtime_ArrayBufferNeuter) {
   HandleScope scope(isolate);
   CONVERT_ARG_HANDLE_CHECKED(JSArrayBuffer, array_buffer, 0);
+  if (array_buffer->backing_store() == NULL) {
+    CHECK(Smi::FromInt(0) == array_buffer->byte_length());
+    return isolate->heap()->undefined_value();
+  }

[Jarin, 2014/03/25 10:59:42]

How about keeping just one return statement? That is, saying something like:

RUNTIME_FUNCTION(MaybeObject*, Runtime_ArrayBufferNeuter) {
  ...
  if (array_buffer->backing_store() != NULL) {
    ... do the neutering...
  }
  CHECK(Smi::FromInt(0) == array_buffer->byte_length());
  return isolate->heap()->undefined_value();
}

[Dmitry Lomov (no reviews), 2014/03/25 11:04:25]

I think that complicates code for the edge case.

[Sven Panne, 2014/03/25 11:30:35]

Actually I like the initial version, too, a "comb-like" pattern is very easy to
read:

void foo() {
   if (special_condition1) return val1;
   if (special_condition2) return val2;
   <compute normal case>
   return normal_case_val;
}

see http://refactoring.com/catalog/replaceNestedConditionalWithGuardClauses.html

   ASSERT(!array_buffer->is_external());
   void* backing_store = array_buffer->backing_store();
   size_t byte_length = NumberToSize(isolate, array_buffer->byte_length());