[stubs] remove unused BranchIfSameValueZero from CodeStubAssembler

src/code-stub-assembler.h

Index: src/code-stub-assembler.h
diff --git a/src/code-stub-assembler.h b/src/code-stub-assembler.h
index 79265793a1993f793fc718933678c7bea4c89185..33b3f330e40f00d3149457d6a4a0b401dd0458d6 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -171,10 +171,6 @@ class CodeStubAssembler : public compiler::CodeAssembler {
                          if_notequal);
   }
 
-  void BranchIfSameValueZero(compiler::Node* a, compiler::Node* b,
-                             compiler::Node* context, Label* if_true,
-                             Label* if_false);
-
   void BranchIfFastJSArray(compiler::Node* object, compiler::Node* context,
                            Label* if_true, Label* if_false);