Big merge from experimental to bleeding edge.

samples/swarm/swarm_ui_lib/layout/GridLayout.dart

Index: samples/swarm/swarm_ui_lib/layout/GridLayout.dart
diff --git a/samples/swarm/swarm_ui_lib/layout/GridLayout.dart b/samples/swarm/swarm_ui_lib/layout/GridLayout.dart
index e70179f677d44b80645564c63a62dd0f2952fd92..10526205733be992aa8ad54b6e2cf2c1cdf0b145 100644
--- a/samples/swarm/swarm_ui_lib/layout/GridLayout.dart
+++ b/samples/swarm/swarm_ui_lib/layout/GridLayout.dart
@@ -154,7 +154,9 @@ class GridLayout extends ViewLayout {
   void _computeUsedBreadthOfTracks(List<GridTrack> tracks) {
 
     // TODO(jmesserly): as a performance optimization we could cache this
-    final items = CollectionUtils.map(view.childViews, (view_) => view_.layout);
+    final items = view.childViews
+        .mappedBy((view_) => view_.layout)
+        .toList();
     CollectionUtils.sortBy(items, (item) => _getSpanCount(item));
 
     // 1. Initialize per Grid Track variables
@@ -254,7 +256,7 @@ class GridLayout extends ViewLayout {
    */
   num _calcNormalizedFractionBreadth(List<GridTrack> tracks) {
 
-    final fractionTracks = tracks.filter((t) => t.maxSizing.isFraction);
+    final fractionTracks = tracks.where((t) => t.maxSizing.isFraction).toList();
 
     // Note: the spec has various bugs in this function, such as mismatched
     // identifiers and names that aren't defined. For the most part it's
@@ -340,8 +342,8 @@ class GridLayout extends ViewLayout {
   void _distributeSpaceBySpanCount(List<ViewLayout> items,
       ContentSizeMode sizeMode, _BreadthAccumulator breadth) {
 
-    items = items.filter((item) =>
-        _hasContentSizedTracks(_getTracks(item), sizeMode, breadth));
+    items = items.where((item) =>
+        _hasContentSizedTracks(_getTracks(item), sizeMode, breadth)).toList();
 
     var tracks = [];
 
@@ -387,7 +389,7 @@ class GridLayout extends ViewLayout {
           sizeMode == ContentSizeMode.MIN && fn.isContentSized) {
 
         // Make sure we don't cross a fractional track
-        return tracks.length == 1 || !tracks.some((t_) => t_.isFractional);
+        return tracks.length == 1 || !tracks.any((t_) => t_.isFractional);
       }
     }
     return false;
@@ -420,7 +422,7 @@ class GridLayout extends ViewLayout {
    * run before the track sizing algorithm.
    */
   void _ensureAllTracks() {
-    final items = CollectionUtils.map(view.childViews, (view_) => view_.layout);
+    final items = view.childViews.mappedBy((view_) => view_.layout);
 
     for (final child in items) {
       if (child.layoutParams == null) {
@@ -437,7 +439,7 @@ class GridLayout extends ViewLayout {
    * Given the track sizes that were computed, position children in the grid.
    */
   void _setBoundsOfChildren() {
-    final items = CollectionUtils.map(view.childViews, (view_) => view_.layout);
+    final items = view.childViews.mappedBy((view_) => view_.layout);
 
     for (final item in items) {
       GridLayoutParams childLayout = item.layoutParams;
@@ -504,7 +506,7 @@ class GridLayout extends ViewLayout {
 
     assert(start >= 0 && span >= 1);
 
-    final result = new List<GridTrack>(span);
+    final result = new List<GridTrack>.fixedLength(span);
     for (int i = 0; i < span; i++) {
       result[i] = tracks[start + i];
     }