Declare more functions returing a MaybeObject* with MUST_USE_RESULT.

No violations found this time.

Additionally I changed one function JSDate::GetField that never returns
a failure to return a Object* instead.
Review URL: https://chromiumcodereview.appspot.com/10383088

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11532 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/objects.cc

@@ -12987,7 +12987,7 @@ int BreakPointInfo::GetBreakPointCount() {
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
-MaybeObject* JSDate::GetField(Object* object, Smi* index) {
+Object* JSDate::GetField(Object* object, Smi* index) {
   return JSDate::cast(object)->DoGetField(
       static_cast<FieldIndex>(index->value()));
 }

src/objects.h

@@ -6139,7 +6139,7 @@ class JSDate: public JSObject {
 
   // Returns the date field with the specified index.
   // See FieldIndex for the list of date fields.
-  static MaybeObject* GetField(Object* date, Smi* index);
+  static Object* GetField(Object* date, Smi* index);
 
   void SetValue(Object* value, bool is_value_nan);