[strong] Refactor ObjectStrength into a replacement for strong boolean args

src/arm/lithium-arm.h

Index: src/arm/lithium-arm.h
diff --git a/src/arm/lithium-arm.h b/src/arm/lithium-arm.h
index 1891d5c2225071433b9823ca5b7beb6f6485ee45..b92f5b6d21565f41963c3ec7d62f430a61ac9572 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -1176,7 +1176,7 @@ class LCmpT final : public LTemplateInstruction<1, 3, 0> {
   DECLARE_CONCRETE_INSTRUCTION(CmpT, "cmp-t")
   DECLARE_HYDROGEN_ACCESSOR(CompareGeneric)
 
-  LanguageMode language_mode() { return hydrogen()->language_mode(); }
+  Strength strength() { return hydrogen()->strength(); }
 
   Token::Value op() const { return hydrogen()->token(); }
 };
@@ -1549,7 +1549,7 @@ class LArithmeticT final : public LTemplateInstruction<1, 3, 0> {
 
   DECLARE_HYDROGEN_ACCESSOR(BinaryOperation)
 
-  LanguageMode language_mode() { return hydrogen()->language_mode(); }
+  Strength strength() { return hydrogen()->strength(); }
 
  private:
   Token::Value op_;