Make DOMWrapperWorld::current() return a reference instead of a pointer

Source/bindings/v8/MIDIAccessResolver.cpp

Index: Source/bindings/v8/MIDIAccessResolver.cpp
diff --git a/Source/bindings/v8/MIDIAccessResolver.cpp b/Source/bindings/v8/MIDIAccessResolver.cpp
index 2ab428882f90185b2ad33d7f36f202a0d5b16c2f..f7c93158d2eb05e8736ab17261a5489e73923430 100644
--- a/Source/bindings/v8/MIDIAccessResolver.cpp
+++ b/Source/bindings/v8/MIDIAccessResolver.cpp
@@ -24,7 +24,7 @@ MIDIAccessResolver::~MIDIAccessResolver()
 void MIDIAccessResolver::resolve(MIDIAccess* access, ExecutionContext* executionContext)
 {
     v8::HandleScope handleScope(toIsolate(executionContext));
-    v8::Context::Scope contextScope(toV8Context(executionContext, m_world.get()));
+    v8::Context::Scope contextScope(toV8Context(executionContext, *m_world));
 
     m_resolver->resolve(access, executionContext);
 }
@@ -32,7 +32,7 @@ void MIDIAccessResolver::resolve(MIDIAccess* access, ExecutionContext* execution
 void MIDIAccessResolver::reject(DOMError* error, ExecutionContext* executionContext)
 {
     v8::HandleScope handleScope(toIsolate(executionContext));
-    v8::Context::Scope contextScope(toV8Context(executionContext, m_world.get()));
+    v8::Context::Scope contextScope(toV8Context(executionContext, *m_world));
 
     m_resolver->reject(error, executionContext);
 }