Remove prototype checks for leaf maps in optimized code.

src/mark-compact.cc

Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index 32516845dfdef73a30032fdf179127097a71ca52..83cbe78d871efdab599db89e788d863524c3d5b4 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -2369,9 +2369,8 @@ void MarkCompactCollector::ClearNonLiveMapTransitions(Map* map,
 void MarkCompactCollector::ClearAndDeoptimizeDependentCodes(Map* map) {
   AssertNoAllocation no_allocation_scope;
   DependentCodes* codes = map->dependent_codes();
-  DependentCodes::GroupStartIndexes starts;
-  codes->ComputeGroupStartIndexes(starts);
-  int number_of_codes = starts[DependentCodes::kGroupCount];
+  DependentCodes::GroupStartIndexes starts(codes);
+  int number_of_codes = starts.at(DependentCodes::kGroupCount);
   if (number_of_codes == 0) return;
   for (int i = 0; i < number_of_codes; i++) {
     Code* code = codes->code_at(i);
@@ -2387,15 +2386,14 @@ void MarkCompactCollector::ClearAndDeoptimizeDependentCodes(Map* map) {
 void MarkCompactCollector::ClearNonLiveDependentCodes(Map* map) {
   AssertNoAllocation no_allocation_scope;
   DependentCodes* codes = map->dependent_codes();
-  DependentCodes::GroupStartIndexes starts;
-  codes->ComputeGroupStartIndexes(starts);
-  int number_of_codes = starts[DependentCodes::kGroupCount];
+  DependentCodes::GroupStartIndexes starts(codes);
+  int number_of_codes = starts.at(DependentCodes::kGroupCount);
   if (number_of_codes == 0) return;
   int new_number_of_codes = 0;
   // Go through all groups, remove dead codes and compact.
   for (int g = 0; g < DependentCodes::kGroupCount; g++) {
     int group_number_of_codes = 0;
-    for (int i = starts[g]; i < starts[g + 1]; i++) {
+    for (int i = starts.at(g); i < starts.at(g + 1); i++) {
       Code* code = codes->code_at(i);
       if (IsMarked(code) && !code->marked_for_deoptimization()) {
         if (new_number_of_codes + group_number_of_codes != i) {