a few small refactorings to closure workarounds

lib/runtime/dart/_interceptors.js

Index: lib/runtime/dart/_interceptors.js
diff --git a/lib/runtime/dart/_interceptors.js b/lib/runtime/dart/_interceptors.js
index bed09a30fbdb678e2c24801f60ebe4b7014ff50f..edbfdf9862473de2ec1ebd65e0ca163b3c918f73 100644
--- a/lib/runtime/dart/_interceptors.js
+++ b/lib/runtime/dart/_interceptors.js
@@ -453,6 +453,11 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
     return JSExtendableArray;
   });
   let JSExtendableArray = JSExtendableArray$();
+  const _isInt32 = Symbol('_isInt32');
+  const _tdivSlow = Symbol('_tdivSlow');
+  const _shlPositive = Symbol('_shlPositive');
+  const _shrOtherPositive = Symbol('_shrOtherPositive');
+  const _shrBothPositive = Symbol('_shrBothPositive');
   class Interceptor extends core.Object {
     Interceptor() {
     }
@@ -460,11 +465,6 @@ dart_library.library('dart/_interceptors', null, /* Imports */[
   dart.setSignature(Interceptor, {
     constructors: () => ({Interceptor: [Interceptor, []]})
   });
-  const _isInt32 = Symbol('_isInt32');
-  const _tdivSlow = Symbol('_tdivSlow');
-  const _shlPositive = Symbol('_shlPositive');
-  const _shrOtherPositive = Symbol('_shrOtherPositive');
-  const _shrBothPositive = Symbol('_shrBothPositive');
   dart.defineExtensionNames([
     'compareTo',
     'isNegative',