Fix typos in sky-drawer and sky-scrollable

Now that I can test these with a touch device, I found a few runtime errors
that are fixed in this CL.

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/948073002

framework/fling-curve.dart

@@ -9,15 +9,19 @@ const double _kDefaultBeta = 172.0;
 const double _kDefaultGamma = 3.7;
 
 double _positionAtTime(double t) {
-  return kDefaultAlpha * math.exp(-kDefaultGamma * t) - kDefaultBeta * t - kDefaultAlpha;
+  return _kDefaultAlpha * math.exp(-_kDefaultGamma * t)
+      - _kDefaultBeta * t
+      - _kDefaultAlpha;
 }
 
 double _velocityAtTime(double t) {
-  return -kDefaultAlpha * kDefaultGamma * math.exp(-kDefaultGamma * t) - kDefaultBeta;
+  return -_kDefaultAlpha * _kDefaultGamma * math.exp(-_kDefaultGamma * t)
+      - _kDefaultBeta;
 }
 
 double _timeAtVelocity(double v) {
-  return -math.log((v + kDefaultBeta) / (-kDefaultAlpha * kDefaultGamma)) / kDefaultGamma;
+  return -math.log((v + _kDefaultBeta) / (-_kDefaultAlpha * _kDefaultGamma))
+      / _kDefaultGamma;
 }
 
 final double _kMaxVelocity = _velocityAtTime(0.0);

framework/sky-drawer.sky

@@ -64,7 +64,7 @@ class SkyDrawer extends SkyElement implements AnimationDelegate {
 
   void shadowRootReady() {
     _mask = shadowRoot.getElementById('mask');
-    _mask.addEventListener('click', _handleMaskClick);
+    _mask.addEventListener('gesturetap', _handleMaskTap);
     _content = shadowRoot.getElementById('content');
     _content.addEventListener('gestureflingstart', _handleFlingStart);
     position = -_kWidth;
@@ -119,7 +119,7 @@ class SkyDrawer extends SkyElement implements AnimationDelegate {
     position = p;
   }
 
-  void _handleMaskClick(_) {
+  void _handleMaskTap(_) {
     close();
   }
 

framework/sky-scrollable.sky

@@ -13,7 +13,7 @@
     position: relative;
   }
   #scrollable {
-    transform: translateY(0);
+    will-change: transform;
   }
   #vbar {
     position: absolute;