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

src/arm64/lithium-arm64.h

Index: src/arm64/lithium-arm64.h
diff --git a/src/arm64/lithium-arm64.h b/src/arm64/lithium-arm64.h
index fcb15526048f0d273dd746ec2ae1a8756019824c..d47a84fffc3638468f87513a3f13a5a1fe11441f 100644
--- a/src/arm64/lithium-arm64.h
+++ b/src/arm64/lithium-arm64.h
@@ -927,7 +927,7 @@ class LCheckInstanceType V8_FINAL : public LTemplateInstruction<0, 1, 1> {
 
 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;
   }