Return Object* instead of MaybeObject* from runtime calls.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index 772b6d69631cd2fc063196373087cd1bba911c14..6728ef4a0f4e78bed7b3b56e3ed7e0f2d286db2a 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -1053,18 +1053,6 @@ ExternalReference ExternalReference::flush_icache_function(Isolate* isolate) {
 }
 
 
-ExternalReference ExternalReference::perform_gc_function(Isolate* isolate) {
-  return
-      ExternalReference(Redirect(isolate, FUNCTION_ADDR(Runtime::PerformGC)));
-}
-
-
-ExternalReference ExternalReference::out_of_memory_function(Isolate* isolate) {
-  return
-      ExternalReference(Redirect(isolate, FUNCTION_ADDR(Runtime::OutOfMemory)));
-}
-
-
 ExternalReference ExternalReference::delete_handle_scope_extensions(
     Isolate* isolate) {
   return ExternalReference(Redirect(