Update handling of ambiguous name references

runtime/vm/intrinsifier_mips.cc

Index: runtime/vm/intrinsifier_mips.cc
===================================================================
--- runtime/vm/intrinsifier_mips.cc	(revision 27310)
+++ runtime/vm/intrinsifier_mips.cc	(working copy)
@@ -176,7 +176,7 @@
 static intptr_t ComputeObjectArrayTypeArgumentsOffset() {
   const Library& core_lib = Library::Handle(Library::CoreLibrary());
   const Class& cls = Class::Handle(
-      core_lib.LookupClassAllowPrivate(Symbols::ObjectArray(), NULL));
+      core_lib.LookupClassAllowPrivate(Symbols::ObjectArray()));
   ASSERT(!cls.IsNull());
   ASSERT(cls.HasTypeArguments());
   ASSERT(cls.NumTypeArguments() == 1);
@@ -1399,7 +1399,7 @@
   const Library& math_lib = Library::Handle(Library::MathLibrary());
   ASSERT(!math_lib.IsNull());
   const Class& random_class = Class::Handle(
-      math_lib.LookupClassAllowPrivate(Symbols::_Random(), NULL));
+      math_lib.LookupClassAllowPrivate(Symbols::_Random()));
   ASSERT(!random_class.IsNull());
   const Field& state_field = Field::ZoneHandle(
       random_class.LookupInstanceField(Symbols::_state()));