fix temp used in postfix ops

lib/runtime/dart/collection.js

 var collection;
 (function(exports) {
   'use strict';
   let _source = Symbol('_source');
   let UnmodifiableListView$ = dart.generic(function(E) {
     class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
       UnmodifiableListView(source) {
         this[_source] = source;
         super.UnmodifiableListBase();
       }
@@ skipping 148 matching lines @@
         return result;
       }
       toList(opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
         let result = growable ? ((_) => {
           _.length = this.length;
           return _;
         }).bind(this)(new core.List()) : new core.List(this.length);
         let i = 0;
         for (let element of this)
-          result.set(((x) => i = dart.notNull(x$) + 1, x$)(i), element);
+          result.set(((x$) => i = dart.notNull(x$) + 1, x$)(i), element);
         return result;
       }
       map(f) {
         return new _internal.EfficientLengthMappedIterable(this, f);
       }
       get single() {
         if (dart.notNull(this.length) > 1)
           throw _internal.IterableElementError.tooMany();
         let it = this.iterator;
         if (!dart.notNull(it.moveNext()))
@@ skipping 1286 matching lines @@
         return result;
       }
       toSet() {
         let result = new core.Set();
         for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
           result.add(this.get(i));
         }
         return result;
       }
       add(element) {
-        this.set(((x) => this.length = dart.notNull(x$) + 1, x$).bind(this)(this.length), element);
+        this.set(((x$) => this.length = dart.notNull(x$) + 1, x$).bind(this)(this.length), element);
       }
       addAll(iterable) {
         for (let element of iterable) {
-          this.set(((x) => this.length = dart.notNull(x$) + 1, x$).bind(this)(this.length), element);
+          this.set(((x$) => this.length = dart.notNull(x$) + 1, x$).bind(this)(this.length), element);
         }
       }
       remove(element) {
         for (let i = 0; dart.notNull(i) < dart.notNull(this.length); i = dart.notNull(i) + 1) {
           if (dart.equals(this.get(i), element)) {
             this.setRange(i, dart.notNull(this.length) - 1, this, dart.notNull(i) + 1);
             this.length = 1;
             return true;
           }
         }
@@ skipping 209 matching lines @@
         let insertionLength = iterable.length;
         this.length = insertionLength;
         this.setRange(dart.notNull(index) + dart.notNull(insertionLength), this.length, this, index);
         this.setAll(index, iterable);
       }
       setAll(index, iterable) {
         if (dart.is(iterable, core.List)) {
           this.setRange(index, dart.notNull(index) + dart.notNull(iterable.length), iterable);
         } else {
           for (let element of iterable) {
-            this.set(((x) => index = dart.notNull(x$) + 1, x$)(index), element);
+            this.set(((x$) => index = dart.notNull(x$) + 1, x$)(index), element);
           }
         }
       }
       get reversed() {
         return new _internal.ReversedListIterable(this);
       }
       toString() {
         return IterableBase.iterableToFullString(this, '[', ']');
       }
     }
@@ skipping 3167 matching lines @@
   exports.LinkedHashMapKeyIterable = LinkedHashMapKeyIterable;
   exports.LinkedHashMapKeyIterable$ = LinkedHashMapKeyIterable$;
   exports.LinkedHashMapKeyIterator = LinkedHashMapKeyIterator;
   exports.LinkedHashMapKeyIterator$ = LinkedHashMapKeyIterator$;
   exports.HashSetIterator = HashSetIterator;
   exports.HashSetIterator$ = HashSetIterator$;
   exports.LinkedHashSetCell = LinkedHashSetCell;
   exports.LinkedHashSetIterator = LinkedHashSetIterator;
   exports.LinkedHashSetIterator$ = LinkedHashSetIterator$;
 })(collection || (collection = {}));