[runtime] Remove the redundant %_IsObject intrinsic.

src/x87/lithium-codegen-x87.h

Index: src/x87/lithium-codegen-x87.h
diff --git a/src/x87/lithium-codegen-x87.h b/src/x87/lithium-codegen-x87.h
index 9157779a95d19601db9bba37e7f99d16a73006b3..45760ddb38e03d437760ed724f2b8bffee1ca31c 100644
--- a/src/x87/lithium-codegen-x87.h
+++ b/src/x87/lithium-codegen-x87.h
@@ -298,14 +298,6 @@ class LCodeGen: public LCodeGenBase {
   // true and false label should be made, to optimize fallthrough.
   Condition EmitTypeofIs(LTypeofIsAndBranch* instr, Register input);
 
-  // Emits optimized code for %_IsObject(x).  Preserves input register.
-  // Returns the condition on which a final split to
-  // true and false label should be made, to optimize fallthrough.
-  Condition EmitIsObject(Register input,
-                         Register temp1,
-                         Label* is_not_object,
-                         Label* is_object);
-
   // Emits optimized code for %_IsString(x).  Preserves input register.
   // Returns the condition on which a final split to
   // true and false label should be made, to optimize fallthrough.