Shorten live ranges of argument subexpressions.

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 41209c67d571b3e9200f78a6c73b6dc2e6dc9cc6..ad0435bfc69ba9fad6f745b93b947c6ba1ad53dd 100644
--- a/src/arm/lithium-arm.h
+++ b/src/arm/lithium-arm.h
@@ -1390,6 +1390,8 @@ class LCallGlobal: public LInstruction {
 
 class LCallKnownGlobal: public LInstruction {
  public:
+  explicit LCallKnownGlobal(LOperand* receiver) : LUnaryOperation(receiver) { }
+
   DECLARE_CONCRETE_INSTRUCTION(CallKnownGlobal, "call-known-global")
   DECLARE_HYDROGEN_ACCESSOR(CallKnownGlobal)
 
@@ -2091,6 +2093,11 @@ class LChunkBuilder BASE_EMBEDDED {
   LInstruction* DoArithmeticT(Token::Value op,
                               HArithmeticBinaryOperation* instr);
 
+  void DecrementArgumentCount(int amount) {
+    ASSERT(amount <= argument_count_);
+    argument_count_ -= amount;
+  }
+
   LChunk* chunk_;
   HGraph* const graph_;
   Status status_;