implement opassign, fix bugs in pre/postfix, introduce a let* helper

lib/runtime/dart/_internal.js

 var _internal;
 (function(exports) {
   'use strict';
   class EfficientLength extends core.Object {}
   let ListIterable$ = dart.generic(function(E) {
     class ListIterable extends collection.IterableBase$(E) {
       ListIterable() {
         super.IterableBase();
       }
       get [core.$iterator]() {
@@ skipping 280 matching lines @@
       }
       [core.$toList](opts) {
         let growable = opts && 'growable' in opts ? opts.growable : true;
         let start = this[_start];
         let end = this[_iterable][core.$length];
         if (this[_endOrLength] != null && dart.notNull(this[_endOrLength]) < dart.notNull(end))
           end = this[_endOrLength];
         let length = dart.notNull(end) - dart.notNull(start);
         if (dart.notNull(length) < 0)
           length = 0;
-        let result = growable ? ((_) => {
+        let result = growable ? (() => {
+          let _ = new (core.List$(E))();
           _[core.$length] = length;
           return _;
-        })(new (core.List$(E))()) : new (core.List$(E))(length);
+        })() : new (core.List$(E))(length);
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           result[core.$set](i, this[_iterable][core.$elementAt](dart.notNull(start) + dart.notNull(i)));
           if (dart.notNull(this[_iterable][core.$length]) < dart.notNull(end))
             throw new core.ConcurrentModificationError(this);
         }
         return dart.as(result, core.List$(E));
       }
     }
     return SubListIterable;
   });
@@ skipping 774 matching lines @@
         if (compare == null)
           compare = core.Comparable.compare;
         Sort.sort(list, compare);
       }
       static shuffleList(list, random) {
         if (random == null)
           random = new math.Random();
         let length = list[core.$length];
         while (dart.notNull(length) > 1) {
           let pos = random.nextInt(length);
-          length = 1;
+          length = dart.notNull(length) - 1;
           let tmp = list[core.$get](length);
           list[core.$set](length, list[core.$get](pos));
           list[core.$set](pos, tmp);
         }
       }
       static indexOfList(list, element, start) {
         return Lists.indexOf(list, element, start, list[core.$length]);
       }
       static lastIndexOfList(list, element, start) {
         if (start == null)
@@ skipping 58 matching lines @@
         for (let i = start; dart.notNull(i) < dart.notNull(end); i = dart.notNull(i) + 1) {
           list[core.$set](i, fillValue);
         }
       }
       static insertAllList(list, index, iterable) {
         core.RangeError.checkValueInInterval(index, 0, list[core.$length], "index");
         if (!dart.is(iterable, EfficientLength)) {
           iterable = iterable[core.$toList]({growable: false});
         }
         let insertionLength = iterable[core.$length];
-        list[core.$length] = insertionLength;
+        list[core.$length] = dart.notNull(list[core.$length]) + dart.notNull(insertionLength);
         list[core.$setRange](dart.notNull(index) + dart.notNull(insertionLength), list[core.$length], list, index);
         for (let element of iterable) {
-          list[core.$set](((x) => index = dart.notNull(x) + 1, x)(index), element);
+          list[core.$set]((() => {
+            let x = index;
+            index = dart.notNull(x) + 1;
+            return x;
+          })(), element);
         }
       }
       static setAllList(list, index, iterable) {
         core.RangeError.checkValueInInterval(index, 0, list[core.$length], "index");
         for (let element of iterable) {
-          list[core.$set](((x) => index = dart.notNull(x) + 1, x)(index), element);
+          list[core.$set]((() => {
+            let x = index;
+            index = dart.notNull(x) + 1;
+            return x;
+          })(), element);
         }
       }
       asMapList(l) {
         return new (ListMapView$(T))(dart.as(l, core.List$(T)));
       }
       static setContainsAll(set, other) {
         for (let element of other) {
           if (!dart.notNull(set[core.$contains](element)))
             return false;
         }
@@ skipping 478 matching lines @@
             }
             less = dart.notNull(less) + 1;
           } else {
             while (true) {
               comp = dart.dinvokef(compare, a[core.$get](great), pivot);
               if (dart.notNull(comp) > 0) {
                 great = dart.notNull(great) - 1;
                 continue;
               } else if (dart.notNull(comp) < 0) {
                 a[core.$set](k, a[core.$get](less));
-                a[core.$set](((x) => less = dart.notNull(x) + 1, x)(less), a[core.$get](great));
-                a[core.$set](((x) => great = dart.notNull(x) - 1, x)(great), ak);
+                a[core.$set]((() => {
+                  let x = less;
+                  less = dart.notNull(x) + 1;
+                  return x;
+                })(), a[core.$get](great));
+                a[core.$set]((() => {
+                  let x = great;
+                  great = dart.notNull(x) - 1;
+                  return x;
+                })(), ak);
                 break;
               } else {
                 a[core.$set](k, a[core.$get](great));
-                a[core.$set](((x) => great = dart.notNull(x) - 1, x)(great), ak);
+                a[core.$set]((() => {
+                  let x = great;
+                  great = dart.notNull(x) - 1;
+                  return x;
+                })(), ak);
                 break;
               }
             }
           }
         }
       } else {
         for (let k = less; dart.notNull(k) <= dart.notNull(great); k = dart.notNull(k) + 1) {
           let ak = a[core.$get](k);
           let comp_pivot1 = dart.dinvokef(compare, ak, pivot1);
           if (dart.notNull(comp_pivot1) < 0) {
             if (k != less) {
               a[core.$set](k, a[core.$get](less));
               a[core.$set](less, ak);
             }
             less = dart.notNull(less) + 1;
           } else {
             let comp_pivot2 = dart.dinvokef(compare, ak, pivot2);
             if (dart.notNull(comp_pivot2) > 0) {
               while (true) {
                 let comp = dart.dinvokef(compare, a[core.$get](great), pivot2);
                 if (dart.notNull(comp) > 0) {
                   great = dart.notNull(great) - 1;
                   if (dart.notNull(great) < dart.notNull(k))
                     break;
                   continue;
                 } else {
                   comp = dart.dinvokef(compare, a[core.$get](great), pivot1);
                   if (dart.notNull(comp) < 0) {
                     a[core.$set](k, a[core.$get](less));
-                    a[core.$set](((x) => less = dart.notNull(x) + 1, x)(less), a[core.$get](great));
-                    a[core.$set](((x) => great = dart.notNull(x) - 1, x)(great), ak);
+                    a[core.$set]((() => {
+                      let x = less;
+                      less = dart.notNull(x) + 1;
+                      return x;
+                    })(), a[core.$get](great));
+                    a[core.$set]((() => {
+                      let x = great;
+                      great = dart.notNull(x) - 1;
+                      return x;
+                    })(), ak);
                   } else {
                     a[core.$set](k, a[core.$get](great));
-                    a[core.$set](((x) => great = dart.notNull(x) - 1, x)(great), ak);
+                    a[core.$set]((() => {
+                      let x = great;
+                      great = dart.notNull(x) - 1;
+                      return x;
+                    })(), ak);
                   }
                   break;
                 }
               }
             }
           }
         }
       }
       a[core.$set](left, a[core.$get](dart.notNull(less) - 1));
       a[core.$set](dart.notNull(less) - 1, pivot1);
@@ skipping 27 matching lines @@
                 let comp = dart.dinvokef(compare, a[core.$get](great), pivot2);
                 if (comp == 0) {
                   great = dart.notNull(great) - 1;
                   if (dart.notNull(great) < dart.notNull(k))
                     break;
                   continue;
                 } else {
                   comp = dart.dinvokef(compare, a[core.$get](great), pivot1);
                   if (dart.notNull(comp) < 0) {
                     a[core.$set](k, a[core.$get](less));
-                    a[core.$set](((x) => less = dart.notNull(x) + 1, x)(less), a[core.$get](great));
-                    a[core.$set](((x) => great = dart.notNull(x) - 1, x)(great), ak);
+                    a[core.$set]((() => {
+                      let x = less;
+                      less = dart.notNull(x) + 1;
+                      return x;
+                    })(), a[core.$get](great));
+                    a[core.$set]((() => {
+                      let x = great;
+                      great = dart.notNull(x) - 1;
+                      return x;
+                    })(), ak);
                   } else {
                     a[core.$set](k, a[core.$get](great));
-                    a[core.$set](((x) => great = dart.notNull(x) - 1, x)(great), ak);
+                    a[core.$set]((() => {
+                      let x = great;
+                      great = dart.notNull(x) - 1;
+                      return x;
+                    })(), ak);
                   }
                   break;
                 }
               }
             }
           }
         }
         Sort[_doSort](a, less, great, compare);
       } else {
         Sort[_doSort](a, less, great, compare);
@@ skipping 120 matching lines @@
   exports.ReversedListIterable = ReversedListIterable;
   exports.UnmodifiableListError = UnmodifiableListError;
   exports.NonGrowableListError = NonGrowableListError;
   exports.makeListFixedLength = makeListFixedLength;
   exports.Lists = Lists;
   exports.printToConsole = printToConsole;
   exports.Sort = Sort;
   exports.Symbol = Symbol;
   exports.POWERS_OF_TEN = POWERS_OF_TEN;
 })(_internal || (_internal = {}));