add checks needed for covariant generics, and List<E>

lib/runtime/dart/_internal.js

Index: lib/runtime/dart/_internal.js
diff --git a/lib/runtime/dart/_internal.js b/lib/runtime/dart/_internal.js
index 8884b3a8160e29721873af07bcbc75ffa935528b..1999fc0f39ba2fe8e426c0432553be678ef487ab 100644
--- a/lib/runtime/dart/_internal.js
+++ b/lib/runtime/dart/_internal.js
@@ -73,7 +73,9 @@ var _internal;
         return false;
       }
       [core.$firstWhere](test, opts) {
+        dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
+        dart.as(orElse, dart.functionType(E, []));
         let length = this[core.$length];
         for (let i = 0; dart.notNull(i) < dart.notNull(length); i = dart.notNull(i) + 1) {
           let element = this[core.$elementAt](i);
@@ -88,7 +90,9 @@ var _internal;
         throw IterableElementError.noElement();
       }
       [core.$lastWhere](test, opts) {
+        dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
+        dart.as(orElse, dart.functionType(E, []));
         let length = this[core.$length];
         for (let i = dart.notNull(length) - 1; dart.notNull(i) >= 0; i = dart.notNull(i) - 1) {
           let element = this[core.$elementAt](i);
@@ -788,19 +792,25 @@ var _internal;
         return false;
       }
       [core.$firstWhere](test, opts) {
+        dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
+        dart.as(orElse, dart.functionType(E, []));
         if (orElse != null)
           return orElse();
         throw IterableElementError.noElement();
       }
       [core.$lastWhere](test, opts) {
+        dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
+        dart.as(orElse, dart.functionType(E, []));
         if (orElse != null)
           return orElse();
         throw IterableElementError.noElement();
       }
       [core.$singleWhere](test, opts) {
+        dart.as(test, dart.functionType(core.bool, [E]));
         let orElse = opts && 'orElse' in opts ? opts.orElse : null;
+        dart.as(orElse, dart.functionType(E, []));
         if (orElse != null)
           return orElse();
         throw IterableElementError.noElement();
@@ -1270,9 +1280,11 @@ var _internal;
         throw new core.UnsupportedError("Cannot change the length of a fixed-length list");
       }
       add(value) {
+        dart.as(value, E);
         throw new core.UnsupportedError("Cannot add to a fixed-length list");
       }
       insert(index, value) {
+        dart.as(value, E);
         throw new core.UnsupportedError("Cannot add to a fixed-length list");
       }
       insertAll(at, iterable) {
@@ -1312,6 +1324,7 @@ var _internal;
   let UnmodifiableListMixin$ = dart.generic(function(E) {
     class UnmodifiableListMixin extends core.Object {
       [core.$set](index, value) {
+        dart.as(value, E);
         throw new core.UnsupportedError("Cannot modify an unmodifiable list");
       }
       set [core.$length](newLength) {
@@ -1321,9 +1334,11 @@ var _internal;
         throw new core.UnsupportedError("Cannot modify an unmodifiable list");
       }
       [core.$add](value) {
+        dart.as(value, E);
         throw new core.UnsupportedError("Cannot add to an unmodifiable list");
       }
       [core.$insert](index, value) {
+        dart.as(value, E);
         throw new core.UnsupportedError("Cannot add to an unmodifiable list");
       }
       [core.$insertAll](at, iterable) {
@@ -1344,6 +1359,7 @@ var _internal;
       [core.$sort](compare) {
         if (compare === void 0)
           compare = null;
+        dart.as(compare, core.Comparator$(E));
         throw new core.UnsupportedError("Cannot modify an unmodifiable list");
       }
       [core.$shuffle](random) {
@@ -1361,6 +1377,7 @@ var _internal;
         throw new core.UnsupportedError("Cannot remove from an unmodifiable list");
       }
       [core.$setRange](start, end, iterable, skipCount) {
+        dart.as(iterable, core.Iterable$(E));
         if (skipCount === void 0)
           skipCount = 0;
         throw new core.UnsupportedError("Cannot modify an unmodifiable list");
@@ -1374,6 +1391,7 @@ var _internal;
       [core.$fillRange](start, end, fillValue) {
         if (fillValue === void 0)
           fillValue = null;
+        dart.as(fillValue, E);
         throw new core.UnsupportedError("Cannot modify an unmodifiable list");
       }
     }
@@ -1445,6 +1463,7 @@ var _internal;
         }
       }
       set(key, value) {
+        dart.as(value, E);
         throw new core.UnsupportedError("Cannot modify an unmodifiable map");
       }
       putIfAbsent(key, ifAbsent) {