Recognize and optimize a.runtimeType == b.runtimeType pattern.

runtime/vm/intermediate_language.cc

Index: runtime/vm/intermediate_language.cc
diff --git a/runtime/vm/intermediate_language.cc b/runtime/vm/intermediate_language.cc
index ab7c878e846a2b9d1be3bdb19ac5608f1ed6a5f1..f4278a505c37358de2f83b9749aa8ef5d5489f68 100644
--- a/runtime/vm/intermediate_language.cc
+++ b/runtime/vm/intermediate_language.cc
@@ -3226,6 +3226,23 @@ void PolymorphicInstanceCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 #endif
 
 
+Definition* StaticCallInstr::Canonicalize(FlowGraph* flow_graph) {
+  if (!FLAG_precompiled_mode) {
+    return this;
+  }
+
+  if (function().recognized_kind() == MethodRecognizer::kObjectRuntimeType) {
+    if (input_use_list() == NULL) {
+      // This function has only environment uses. In precompiled mode it is
+      // fine to remove it - because we will never deoptimize.
+      return flow_graph->constant_dead();
+    }
+  }
+
+  return this;
+}
+
+
 LocationSummary* StaticCallInstr::MakeLocationSummary(Zone* zone,
                                                       bool optimizing) const {
   return MakeCallSummary(zone);