Use package:sky imports consistently

sky/sdk/lib/rendering/flex.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:math' as math;
 
-import 'box.dart';
-import 'object.dart';
+import 'package:sky/rendering/box.dart';
+import 'package:sky/rendering/object.dart';
 
 class FlexBoxParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> {
   int flex;
 
   void merge(FlexBoxParentData other) {
     if (other.flex != null)
       flex = other.flex;
     super.merge(other);
   }
 
@@ skipping 139 matching lines @@
       RenderBox child = firstChild;
       while (child != null) {
         int flex = _getFlex(child);
         totalFlex += flex;
         double mainSize;
         double crossSize;
         if (flex == 0) {
           switch (_direction) {
               case FlexDirection.horizontal:
                 mainSize = child.getMaxIntrinsicWidth(childConstraints);
-                BoxConstraints widthConstraints = 
+                BoxConstraints widthConstraints =
                   new BoxConstraints(minWidth: mainSize, maxWidth: mainSize);
                 crossSize = child.getMaxIntrinsicHeight(widthConstraints);
                 break;
               case FlexDirection.vertical:
                 mainSize = child.getMaxIntrinsicHeight(childConstraints);
-                BoxConstraints heightConstraints = 
+                BoxConstraints heightConstraints =
                   new BoxConstraints(minWidth: mainSize, maxWidth: mainSize);
                 crossSize = child.getMaxIntrinsicWidth(heightConstraints);
                 break;
           }
           inflexibleSpace += mainSize;
           maxCrossSize = math.max(maxCrossSize, crossSize);
         }
         assert(child.parentData is FlexBoxParentData);
         child = child.parentData.nextSibling;
       }
 
       // Determine the spacePerFlex by allocating the remaining available space
       double spacePerFlex = (availableMainSpace - inflexibleSpace) / totalFlex;
 
       // Size remaining items, find the maximum cross size
       child = firstChild;
       while (child != null) {
         int flex = _getFlex(child);
         if (flex > 0) {
           double childMainSize = spacePerFlex * flex;
           double crossSize;
           switch (_direction) {
             case FlexDirection.horizontal:
-              BoxConstraints childConstraints = 
+              BoxConstraints childConstraints =
                 new BoxConstraints(minWidth: childMainSize, maxWidth: childMainSize);
               crossSize = child.getMaxIntrinsicHeight(childConstraints);
               break;
             case FlexDirection.vertical:
               BoxConstraints childConstraints =
                 new BoxConstraints(minHeight: childMainSize, maxHeight: childMainSize);
               crossSize = child.getMaxIntrinsicWidth(childConstraints);
               break;
           }
           maxCrossSize = math.max(maxCrossSize, crossSize);
@@ skipping 203 matching lines @@
   }
 
   void hitTestChildren(HitTestResult result, { Point position }) {
     defaultHitTestChildren(result, position: position);
   }
 
   void paint(PaintingCanvas canvas, Offset offset) {
     defaultPaint(canvas, offset);
   }
 }