fixes #131, use before define from variables to classes

lib/runtime/dart/_interceptors.js

 var _interceptors = dart.defineLibrary(_interceptors, {});
 var core = dart.import(core);
 var _js_helper = dart.lazyImport(_js_helper);
 var _internal = dart.import(_internal);
 var _foreign_helper = dart.import(_foreign_helper);
 var _js_embedded_names = dart.import(_js_embedded_names);
 (function(exports, core, _js_helper, _internal, _foreign_helper, _js_embedded_names) {
   'use strict';
   let JSArray = Array;
   let JSMutableArray$ = dart.generic(function(E) {
     class JSMutableArray extends JSArray$(E) {
       JSMutableArray() {
         super.JSArray();
       }
     }
     JSMutableArray[dart.implements] = () => [JSMutableIndexable];
     return JSMutableArray;
   });
   let JSMutableArray = JSMutableArray$();
   let JSFixedArray$ = dart.generic(function(E) {
     class JSFixedArray extends JSMutableArray$(E) {}
     return JSFixedArray;
   });
   let JSFixedArray = JSFixedArray$();
   let JSExtendableArray$ = dart.generic(function(E) {
     class JSExtendableArray extends JSMutableArray$(E) {}
     return JSExtendableArray;
   });
   let JSExtendableArray = JSExtendableArray$();
-  let _isInt32 = Symbol('_isInt32');
-  let _tdivFast = Symbol('_tdivFast');
-  let _tdivSlow = Symbol('_tdivSlow');
-  let _shlPositive = Symbol('_shlPositive');
-  let _shrReceiverPositive = Symbol('_shrReceiverPositive');
-  let _shrOtherPositive = Symbol('_shrOtherPositive');
-  let _shrBothPositive = Symbol('_shrBothPositive');
   class Interceptor extends core.Object {
     Interceptor() {
     }
     ['=='](other) {
       return core.identical(this, other);
     }
     get hashCode() {
       return _js_helper.Primitives.objectHashCode(this);
     }
     toString() {
       return _js_helper.Primitives.objectToString(this);
     }
     noSuchMethod(invocation) {
       throw new core.NoSuchMethodError(this, invocation.memberName, invocation.positionalArguments, invocation.namedArguments);
     }
     get runtimeType() {
       return _js_helper.getRuntimeType(this);
     }
   }
+  let _isInt32 = Symbol('_isInt32');
+  let _tdivFast = Symbol('_tdivFast');
+  let _tdivSlow = Symbol('_tdivSlow');
+  let _shlPositive = Symbol('_shlPositive');
+  let _shrReceiverPositive = Symbol('_shrReceiverPositive');
+  let _shrOtherPositive = Symbol('_shrOtherPositive');
+  let _shrBothPositive = Symbol('_shrBothPositive');
   class JSNumber extends Interceptor {
     JSNumber() {
       super.Interceptor();
     }
     compareTo(b) {
       if (!dart.is(b, core.num))
         throw new core.ArgumentError(b);
       if (this['<'](b)) {
         return -1;
       } else if (this['>'](b)) {
@@ skipping 989 matching lines @@
     }
   }
   // Exports:
   exports.JSArray = JSArray;
   exports.JSMutableArray$ = JSMutableArray$;
   exports.JSMutableArray = JSMutableArray;
   exports.JSFixedArray$ = JSFixedArray$;
   exports.JSFixedArray = JSFixedArray;
   exports.JSExtendableArray$ = JSExtendableArray$;
   exports.JSExtendableArray = JSExtendableArray;
+  exports.Interceptor = Interceptor;
   exports.JSNumber = JSNumber;
-  exports.Interceptor = Interceptor;
   exports.JSInt = JSInt;
   exports.JSDouble = JSDouble;
   exports.JSPositiveInt = JSPositiveInt;
   exports.JSUInt32 = JSUInt32;
   exports.JSUInt31 = JSUInt31;
   exports.JSString = JSString;
   exports.getInterceptor = getInterceptor;
   exports.getDispatchProperty = getDispatchProperty;
   exports.setDispatchProperty = setDispatchProperty;
   exports.makeDispatchRecord = makeDispatchRecord;
   exports.dispatchRecordInterceptor = dispatchRecordInterceptor;
   exports.dispatchRecordProto = dispatchRecordProto;
   exports.dispatchRecordExtension = dispatchRecordExtension;
   exports.dispatchRecordIndexability = dispatchRecordIndexability;
   exports.getNativeInterceptor = getNativeInterceptor;
   exports.findIndexForNativeSubclassType = findIndexForNativeSubclassType;
   exports.findInterceptorConstructorForType = findInterceptorConstructorForType;
   exports.findConstructorForNativeSubclassType = findConstructorForNativeSubclassType;
   exports.findInterceptorForType = findInterceptorForType;
   exports.JSBool = JSBool;
   exports.JSNull = JSNull;
   exports.JSIndexable = JSIndexable;
   exports.JSMutableIndexable = JSMutableIndexable;
   exports.JSObject = JSObject;
   exports.JavaScriptObject = JavaScriptObject;
   exports.PlainJavaScriptObject = PlainJavaScriptObject;
   exports.UnknownJavaScriptObject = UnknownJavaScriptObject;
 })(_interceptors, core, _js_helper, _internal, _foreign_helper, _js_embedded_names);