Roll Observatory deps (charted -> ^0.3.0)

packages/charted/lib/charts/layout_renderers/layout_base_renderer.dart

 //
 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 //
 
 part of charted.charts;
 
@@ skipping 99 matching lines @@
               : ChartState.VAL_UNHIGHLIGHTED;
         }
         if (state.preview == i) {
           flags |= ChartState.VAL_HOVERED;
         }
       }
       _valueStateCache[i] = flags;
     }
   }
 
-  Iterable<String> stylesForValue(int row, { bool isTail: false }) {
-    if (isTail == true) return const[];
+  Iterable<String> stylesForValue(int row, {bool isTail: false}) {
+    if (isTail == true) return const [];
     if (_valueStylesCache[row] == null) {
       if (state == null) {
-        _valueStylesCache[row] = const[];
+        _valueStylesCache[row] = const [];
       } else {
-        var styles = [],
-            flags = _valueStateCache[row];
+        var styles = [], flags = _valueStateCache[row];
 
         if (flags & ChartState.VAL_HIGHLIGHTED != 0) {
           styles.add(ChartState.VAL_HIGHLIGHTED_CLASS);
         } else if (flags & ChartState.VAL_UNHIGHLIGHTED != 0) {
           styles.add(ChartState.VAL_UNHIGHLIGHTED_CLASS);
         }
         if (flags & ChartState.VAL_HOVERED != 0) {
           styles.add(ChartState.VAL_HOVERED_CLASS);
         }
 
         _valueStylesCache[row] = styles;
       }
     }
     return _valueStylesCache[row];
   }
 
   String colorForValue(int row, {bool isTail: false}) => isTail
       ? theme.getOtherColor()
       : theme.getColorForKey(row, _valueStateCache[row]);
 }