VM: Fix bug in the new edge counter code on ARM and MIPS.

runtime/vm/flow_graph_compiler_mips.cc

Index: runtime/vm/flow_graph_compiler_mips.cc
diff --git a/runtime/vm/flow_graph_compiler_mips.cc b/runtime/vm/flow_graph_compiler_mips.cc
index 05cbcc0a9a09295f54d76494fdd96403b0c31e9b..1496565a217c6e2d7f8aefb74ff53cb245cff86a 100644
--- a/runtime/vm/flow_graph_compiler_mips.cc
+++ b/runtime/vm/flow_graph_compiler_mips.cc
@@ -1207,9 +1207,9 @@ void FlowGraphCompiler::EmitEdgeCounter(intptr_t edge_id) {
   ASSERT(!edge_counters_array_.IsNull());
   __ Comment("Edge counter");
   __ LoadObject(T0, edge_counters_array_);
-  __ lw(T1, FieldAddress(T0, Array::element_offset(edge_id)));
+  __ LoadFieldFromOffset(T1, T0, Array::element_offset(edge_id));
   __ AddImmediate(T1, T1, Smi::RawValue(1));
-  __ sw(T1, FieldAddress(T0, Array::element_offset(edge_id)));
+  __ StoreFieldToOffset(T1, T0, Array::element_offset(edge_id));
 }