Various little cleanups to avoid excessive allocation of handles.

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
===================================================================
--- runtime/vm/flow_graph_optimizer.cc	(revision 14483)
+++ runtime/vm/flow_graph_optimizer.cc	(working copy)
@@ -273,7 +273,8 @@
 
 static bool ICDataHasReceiverClassId(const ICData& ic_data, intptr_t class_id) {
   ASSERT(ic_data.num_args_tested() > 0);
-  for (intptr_t i = 0; i < ic_data.NumberOfChecks(); i++) {
+  const intptr_t len = ic_data.NumberOfChecks();
+  for (intptr_t i = 0; i < len; i++) {
     const intptr_t test_class_id = ic_data.GetReceiverClassIdAt(i);
     if (test_class_id == class_id) {
       return true;
@@ -291,7 +292,8 @@
   if (ic_data.num_args_tested() != 2) return false;
 
   Function& target = Function::Handle();
-  for (intptr_t i = 0; i < ic_data.NumberOfChecks(); i++) {
+  const intptr_t len = ic_data.NumberOfChecks();
+  for (intptr_t i = 0; i < len; i++) {
     GrowableArray<intptr_t> class_ids;
     ic_data.GetCheckAt(i, &class_ids, &target);
     ASSERT(class_ids.length() == 2);
@@ -323,7 +325,8 @@
     const GrowableArray<intptr_t>& argument_class_ids) {
   if (ic_data.num_args_tested() != 2) return false;
   Function& target = Function::Handle();
-  for (intptr_t i = 0; i < ic_data.NumberOfChecks(); i++) {
+  const intptr_t len = ic_data.NumberOfChecks();
+  for (intptr_t i = 0; i < len; i++) {
     GrowableArray<intptr_t> class_ids;
     ic_data.GetCheckAt(i, &class_ids, &target);
     ASSERT(class_ids.length() == 2);
@@ -447,7 +450,8 @@
   if (ic_data.NumberOfChecks() == 0) return false;
   GrowableArray<intptr_t> class_ids;
   Function& target = Function::Handle();
-  for (intptr_t i = 0; i < ic_data.NumberOfChecks(); i++) {
+  const intptr_t len = ic_data.NumberOfChecks();
+  for (intptr_t i = 0; i < len; i++) {
     ic_data.GetCheckAt(i, &class_ids, &target);
     if (class_ids[arg_n] != kSmiCid) return false;
   }
@@ -1171,7 +1175,8 @@
       ICData::ZoneHandle(instr->ic_data()->AsUnaryClassChecks());
   if ((unary_checks.NumberOfChecks() > FLAG_max_polymorphic_checks) &&
       InstanceCallNeedsClassCheck(instr)) {
-    // Too many checks, leave it megamorphic.
+    // Too many checks, it will be megamorphic which needs unary checks.
+    instr->set_ic_data(&unary_checks);
     return;
   }