Normalize import paths for Sky modules

sky/framework/sky-scrollable.sky

 <!--
 // 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 src="/sky/framework/sky-element/sky-element.sky" as="SkyElement" />
-<import src="/sky/framework/fling-curve.sky" as="FlingCurve" />
+<import src="sky-element/sky-element.sky" as="SkyElement" />
+<import src="fling-curve.sky" as="FlingCurve" />
 
 <sky-element
   name="sky-scrollable"
   on-gesturescrollstart="handleScrollStart_"
   on-gesturescrollend="handleScrollEnd_"
   on-gesturescrollupdate="handleScrollUpdate_"
   on-gestureflingstart="handleFlingStart_"
   on-gestureflingcancel="handleFlingCancel_"
   on-wheel="handleWheel_">
 <template>
@@ skipping 104 matching lines @@
   handleFlingCancel_(event) {
     this.stopFling_();
   }
 
   handleWheel_(event) {
     this.scrollBy(-event.offsetY);
   }
 }.register();
 </script>
 </sky-element>