Only assign environments when they are actually needed. (ARM and ARM64 only)

src/arm64/lithium-arm64.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 909 matching lines @@
   LOperand* value() { return inputs_[0]; }
   LOperand* temp() { return temps_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(CheckInstanceType, "check-instance-type")
   DECLARE_HYDROGEN_ACCESSOR(CheckInstanceType)
 };
 
 
 class LCheckMaps V8_FINAL : public LTemplateInstruction<0, 1, 1> {
  public:
-  explicit LCheckMaps(LOperand* value, LOperand* temp = NULL) {
+  explicit LCheckMaps(LOperand* value, LOperand* temp) {
     inputs_[0] = value;
     temps_[0] = temp;
   }
 
   LOperand* value() { return inputs_[0]; }
   LOperand* temp() { return temps_[0]; }
 
   DECLARE_CONCRETE_INSTRUCTION(CheckMaps, "check-maps")
   DECLARE_HYDROGEN_ACCESSOR(CheckMaps)
 };
@@ skipping 2150 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(LChunkBuilder);
 };
 
 #undef DECLARE_HYDROGEN_ACCESSOR
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM64_LITHIUM_ARM64_H_