Replace HCheckPrototypeMaps by explicit map checks of constant values.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 4ecb733508ebb544099c352acd67045dc2c32d7f..84c642cbc9e7600b11343872735370e23ec0e0a4 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1920,15 +1920,6 @@ LInstruction* LChunkBuilder::DoCheckInstanceType(HCheckInstanceType* instr) {
 }
 
 
-LInstruction* LChunkBuilder::DoCheckPrototypeMaps(HCheckPrototypeMaps* instr) {
-  LUnallocated* temp = NULL;
-  if (!instr->CanOmitPrototypeChecks()) temp = TempRegister();
-  LCheckPrototypeMaps* result = new(zone()) LCheckPrototypeMaps(temp);
-  if (instr->CanOmitPrototypeChecks()) return result;
-  return AssignEnvironment(result);
-}
-
-
 LInstruction* LChunkBuilder::DoCheckFunction(HCheckFunction* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
   return AssignEnvironment(new(zone()) LCheckFunction(value));