[crankshaft] Generate lazy bailout point for HProlog instruction only when it is necessary.

src/crankshaft/ppc/lithium-ppc.cc

Index: src/crankshaft/ppc/lithium-ppc.cc
diff --git a/src/crankshaft/ppc/lithium-ppc.cc b/src/crankshaft/ppc/lithium-ppc.cc
index 214e7711cade7030727af81cf1ca8aa4d473c730..93cdc8450db597bbb2bfcbd4c287448f71736531 100644
--- a/src/crankshaft/ppc/lithium-ppc.cc
+++ b/src/crankshaft/ppc/lithium-ppc.cc
@@ -890,7 +890,7 @@ void LChunkBuilder::AddInstruction(LInstruction* instr,
   }
   chunk_->AddInstruction(instr, current_block_);
 
-  if (instr->IsCall() || instr->IsPrologue()) {
+  if (instr->IsCall()) {
     HValue* hydrogen_value_for_lazy_bailout = hydrogen_val;
     if (hydrogen_val->HasObservableSideEffects()) {
       HSimulate* sim = HSimulate::cast(hydrogen_val->next());
@@ -905,7 +905,11 @@ void LChunkBuilder::AddInstruction(LInstruction* instr,
 
 
 LInstruction* LChunkBuilder::DoPrologue(HPrologue* instr) {
-  return new (zone()) LPrologue();
+  LInstruction* result = new (zone()) LPrologue();
+  if (info_->num_heap_slots() > 0) {
+    result = MarkAsCall(result, instr);
+  }
+  return result;
 }