Let the embedder store arbitrary Values via Context::SetData

In WebKit, we would like to store a void* to a data structure that contains
lots of exciting per-context data. The current API restricts us to storing only
Strings, which is less useful.

I've also cleaned up the implementation of GetData to be less convoluted.

Review URL: https://codereview.chromium.org/10907189
Patch from Adam Barth <abarth@chromium.org>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12520 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

include/v8.h

@@ -3718,7 +3718,7 @@ class V8EXPORT Context {
    * with the debugger to provide additional information on the context through
    * the debugger API.
    */
-  void SetData(Handle<String> data);
+  void SetData(Handle<Value> data);
   Local<Value> GetData();
 
   /**

src/api.cc

@@ -765,7 +765,7 @@ void Context::Exit() {
 }
 
 
-void Context::SetData(v8::Handle<String> data) {
+void Context::SetData(v8::Handle<Value> data) {
   i::Handle<i::Context> env = Utils::OpenHandle(this);
   i::Isolate* isolate = env->GetIsolate();
   if (IsDeadCheck(isolate, "v8::Context::SetData()")) return;
@@ -781,16 +781,13 @@ v8::Local<v8::Value> Context::GetData() {
   i::Handle<i::Context> env = Utils::OpenHandle(this);
   i::Isolate* isolate = env->GetIsolate();
   if (IsDeadCheck(isolate, "v8::Context::GetData()")) {
-    return v8::Local<Value>();
+    return Local<Value>();
   }
-  i::Object* raw_result = NULL;
   ASSERT(env->IsNativeContext());
-  if (env->IsNativeContext()) {
-    raw_result = env->data();
-  } else {
+  if (!env->IsNativeContext()) {
     return Local<Value>();
   }
-  i::Handle<i::Object> result(raw_result, isolate);
+  i::Handle<i::Object> result(env->data(), isolate);
   return Utils::ToLocal(result);
 }