[es6] Consistently use %_GetSuperConstructor to implement super calls.

src/full-codegen/mips/full-codegen-mips.cc

Index: src/full-codegen/mips/full-codegen-mips.cc
diff --git a/src/full-codegen/mips/full-codegen-mips.cc b/src/full-codegen/mips/full-codegen-mips.cc
index e2259dfa33d75fb3731edabc514d434faf3720d1..0d5cc7c9ec18ca46c38f58d6b0d46031c387041a 100644
--- a/src/full-codegen/mips/full-codegen-mips.cc
+++ b/src/full-codegen/mips/full-codegen-mips.cc
@@ -3003,8 +3003,15 @@ void FullCodeGenerator::EmitSuperConstructorCall(Call* expr) {
       expr->expression()->AsSuperCallReference();
   DCHECK_NOT_NULL(super_call_ref);
 
-  EmitLoadSuperConstructor(super_call_ref);
-  __ push(result_register());
+  // Push the super constructor target on the stack (may be null,
+  // but the Construct builtin can deal with that properly).
+  VisitForAccumulatorValue(super_call_ref->this_function_var());
+  __ AssertFunction(result_register());
+  __ lw(result_register(),
+        FieldMemOperand(result_register(), HeapObject::kMapOffset));
+  __ lw(result_register(),
+        FieldMemOperand(result_register(), Map::kPrototypeOffset));
+  __ Push(result_register());
 
   // Push the arguments ("left-to-right") on the stack.
   ZoneList<Expression*>* args = expr->arguments();