Get rid of the HInstanceSize instruction.

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index 36e9bdfa6566f977a2f9fec4d23a6a9eafc7f558..0de9ea5ac8068ce8c31d955c699729bb475e2fe0 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -105,7 +105,6 @@ class LCodeGen;
   V(InnerAllocatedObject)                       \
   V(InstanceOf)                                 \
   V(InstanceOfKnownGlobal)                      \
-  V(InstanceSize)                               \
   V(InstructionGap)                             \
   V(Integer32ToDouble)                          \
   V(Integer32ToSmi)                             \
@@ -1078,19 +1077,6 @@ class LInstanceOfKnownGlobal V8_FINAL : public LTemplateInstruction<1, 1, 1> {
 };
 
 
-class LInstanceSize V8_FINAL : public LTemplateInstruction<1, 1, 0> {
- public:
-  explicit LInstanceSize(LOperand* object) {
-    inputs_[0] = object;
-  }
-
-  LOperand* object() { return inputs_[0]; }
-
-  DECLARE_CONCRETE_INSTRUCTION(InstanceSize, "instance-size")
-  DECLARE_HYDROGEN_ACCESSOR(InstanceSize)
-};
-
-
 class LBoundsCheck V8_FINAL : public LTemplateInstruction<0, 2, 0> {
  public:
   LBoundsCheck(LOperand* index, LOperand* length) {