Remove HCompareConstantEqAndBranch (never used), and its corresponding Lithium instructions.

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index d1bb4aa97570183f993313c476e2d3b7db705cb5..3ce132a3df5da61f5c1ee6dea1167da2aaa7d7fb 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -2426,14 +2426,6 @@ void LCodeGen::DoCmpObjectEqAndBranch(LCmpObjectEqAndBranch* instr) {
 }
 
 
-void LCodeGen::DoCmpConstantEqAndBranch(LCmpConstantEqAndBranch* instr) {
-  Register left = ToRegister(instr->left());
-
-  __ cmp(left, instr->hydrogen()->right());
-  EmitBranch(instr, equal);
-}
-
-
 Condition LCodeGen::EmitIsObject(Register input,
                                  Register temp1,
                                  Label* is_not_object,