[turbofan] Use range types to type and lower arithmetic ops.

src/compiler/typer.h

Index: src/compiler/typer.h
diff --git a/src/compiler/typer.h b/src/compiler/typer.h
index 5ca4d7cdcb6243e1c225bfa51b74276c66d7d835..994beb87593fbbbb18ac3b0bace01e72f53c8339 100644
--- a/src/compiler/typer.h
+++ b/src/compiler/typer.h
@@ -51,6 +51,7 @@ class Typer {
   Type* zeroish;
   Type* falsish;
   Type* integer;
+  Type* weakint;
   Type* number_fun0_;
   Type* number_fun1_;
   Type* number_fun2_;
@@ -67,6 +68,9 @@ class Typer {
   Type* uint32_array_fun_;
   Type* float32_array_fun_;
   Type* float64_array_fun_;
+
+  ZoneVector<Handle<Object> > weaken_min_limits_;
+  ZoneVector<Handle<Object> > weaken_max_limits_;
 };
 }
 }