Change integer canonicalization to use CheckAndCanonicalize

runtime/lib/integers.cc

Index: runtime/lib/integers.cc
diff --git a/runtime/lib/integers.cc b/runtime/lib/integers.cc
index 4ee0a0cd14fb1428592d0be6d418b007f677e7f7..4e64ea5ae04a625956daee125dd9f2c7cf296d94 100644
--- a/runtime/lib/integers.cc
+++ b/runtime/lib/integers.cc
@@ -248,8 +248,7 @@ DEFINE_NATIVE_ENTRY(Integer_fromEnvironment, 3) {
       const Integer& result = Integer::Handle(ParseInteger(value));
       if (!result.IsNull()) {
         if (result.IsSmi()) return result.raw();
-        return Integer::NewCanonical(String::Handle(
-            String::New(result.ToCString())));
+        return result.CheckAndCanonicalize(NULL);
       }
     } else if (Dart_IsError(response)) {
       const Object& error =