Inline instanceOf and 'as' operations; fix a bug in code emission

runtime/vm/flow_graph_compiler_arm.cc

Index: runtime/vm/flow_graph_compiler_arm.cc
diff --git a/runtime/vm/flow_graph_compiler_arm.cc b/runtime/vm/flow_graph_compiler_arm.cc
index 71bb862b3234fc01261e3c04bf6f33d3507f8bc4..8c6c4113aeb9d786489c44d46ca0c3fac3a6fc2c 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -608,7 +608,7 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t token_pos,
     // time, since an uninstantiated type at compile time could be Object or
     // dynamic at run time.
     __ CompareImmediate(R0, reinterpret_cast<int32_t>(Object::null()));
-    __ b(&is_not_instance, EQ);
+    __ b(type.IsNullType() ? &is_instance : &is_not_instance, EQ);
   }
 
   // Generate inline instanceof test.