[stubs] Use CSA::IsHeapNumberMap() instead of manual map comparing.

src/builtins/builtins-math.cc

Index: src/builtins/builtins-math.cc
diff --git a/src/builtins/builtins-math.cc b/src/builtins/builtins-math.cc
index 3cf0d90d30cd6a3347266164ade849329f0fafc5..82c489476841ed70440a68c73b7d72b7984f1f3d 100644
--- a/src/builtins/builtins-math.cc
+++ b/src/builtins/builtins-math.cc
@@ -81,8 +81,7 @@ void Builtins::Generate_MathAbs(compiler::CodeAssemblerState* state) {
       // Check if {x} is a HeapNumber.
       Label if_xisheapnumber(&assembler),
           if_xisnotheapnumber(&assembler, Label::kDeferred);
-      assembler.Branch(assembler.WordEqual(assembler.LoadMap(x),
-                                           assembler.HeapNumberMapConstant()),
+      assembler.Branch(assembler.IsHeapNumberMap(assembler.LoadMap(x)),
                        &if_xisheapnumber, &if_xisnotheapnumber);
 
       assembler.Bind(&if_xisheapnumber);
@@ -140,10 +139,8 @@ void Generate_MathRoundingOperation(
       // Check if {x} is a HeapNumber.
       Label if_xisheapnumber(assembler),
           if_xisnotheapnumber(assembler, Label::kDeferred);
-      assembler->Branch(
-          assembler->WordEqual(assembler->LoadMap(x),
-                               assembler->HeapNumberMapConstant()),
-          &if_xisheapnumber, &if_xisnotheapnumber);
+      assembler->Branch(assembler->IsHeapNumberMap(assembler->LoadMap(x)),
+                        &if_xisheapnumber, &if_xisnotheapnumber);
 
       assembler->Bind(&if_xisheapnumber);
       {
@@ -281,8 +278,7 @@ void Builtins::Generate_MathClz32(compiler::CodeAssemblerState* state) {
       // Check if {x} is a HeapNumber.
       Label if_xisheapnumber(&assembler),
           if_xisnotheapnumber(&assembler, Label::kDeferred);
-      assembler.Branch(assembler.WordEqual(assembler.LoadMap(x),
-                                           assembler.HeapNumberMapConstant()),
+      assembler.Branch(assembler.IsHeapNumberMap(assembler.LoadMap(x)),
                        &if_xisheapnumber, &if_xisnotheapnumber);
 
       assembler.Bind(&if_xisheapnumber);