Fix a segment-fault caused by Value::IntegerValue

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 1cf5d529119ce42fa92a1f65767ccba8153fb6fc..b23c2a117c95a79d779e9d8c7116debed6838049 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -3264,14 +3264,16 @@ Maybe<int64_t> Value::IntegerValue(Local<Context> context) const {
   i::Handle<i::Object> num;
   if (obj->IsNumber()) {
     num = obj;
+    return Just(num->IsSmi() ? static_cast<int64_t>(i::Smi::cast(*num)->value())
+                             : static_cast<int64_t>(num->Number()));
   } else {
     PREPARE_FOR_EXECUTION_PRIMITIVE(context, "IntegerValue", int64_t);
     has_pending_exception =

[jochen (gone - plz use gerrit), 2015/09/09 14:16:59]

can you pull the if() case in here instead of duplicating the returns?

something like

PREPARE_FOR...
if (obj->isNumber())
 num = obj;
else {
 has_pending = ...

[noordhuis, 2015/09/09 23:35:56]

That pessimizes the common case when the input is a SMI or double. 
PREPARE_FOR_EXECUTION_PRIMITIVE mutates a couple of per-isolate data structures
and is fairly heavy-weight.

         !i::Execution::ToInteger(isolate, obj).ToHandle(&num);
     RETURN_ON_FAILED_EXECUTION_PRIMITIVE(int64_t);
+    return Just(num->IsSmi() ? static_cast<int64_t>(i::Smi::cast(*num)->value())
+                             : static_cast<int64_t>(num->Number()));
   }
-  return Just(num->IsSmi() ? static_cast<int64_t>(i::Smi::cast(*num)->value())
-                           : static_cast<int64_t>(num->Number()));
 }