title: flutter not compiling with different colored border sides
body: <p>I'm getting started with flutter and want to create a widget which has different colored borders on each side depending on a condition.</p>
  
  <pre><code>decoration: new BoxDecoration(
   border: new Border(
    top: new BorderSide(width: 1.0, color: Colors.red),
    left: new BorderSide(width: 1.0, color: Colors.red),
    right: new BorderSide(width: 1.0, color: Colors.red),
    bottom: new BorderSide(width: 1.0, color: Colors.white)
   ),
   borderRadius: new BorderRadius.only(
    topLeft: new Radius.circular(15.0)
   ),
  ),
  </code></pre>
  
  <p>whenever I try to use more than one color on the borders in breaks and I'm not sure why but works fine if they all are one single color.</p>
  
  <p>I get the following error on the hot reload :</p>
  
  <pre><code>
  I/flutter ( 1274): The following RenderObject was being processed when the exception was fired: RenderDecoratedBox#746f5 relayoutBoundary=up5:
  I/flutter ( 1274):   creator: DecoratedBox ← Container ← Row ← Column ← Container ← Column ← Center ← MediaQuery ←
  I/flutter ( 1274):     LayoutId-[&lt;_ScaffoldSlot.body&gt;] ← CustomMultiChildLayout ← AnimatedBuilder ← DefaultTextStyle ← ⋯
  I/flutter ( 1274):   parentData: offset=Offset(140.2, 0.0); flex=null; fit=null (can use size)
  I/flutter ( 1274):   constraints: BoxConstraints(unconstrained)
  I/flutter ( 1274):   size: Size(57.0, 38.0)
  I/flutter ( 1274):   decoration: BoxDecoration:
  I/flutter ( 1274):     border: Border(top: BorderSide(MaterialColor(primary value: Color(0xfff44336)), 1.0,
  I/flutter ( 1274):       BorderStyle.solid), right: BorderSide(MaterialColor(primary value: Color(0xff4caf50)), 1.0,
  I/flutter ( 1274):       BorderStyle.solid), bottom: BorderSide(MaterialColor(primary value: Color(0xff4caf50)), 1.0,
  I/flutter ( 1274):       BorderStyle.solid), left: BorderSide(MaterialColor(primary value: Color(0xfff44336)), 1.0,
  I/flutter ( 1274):       BorderStyle.solid))
  I/flutter ( 1274):     borderRadius: BorderRadius.only(topLeft: Radius.circular(15.0))
  I/flutter ( 1274):   configuration: ImageConfiguration(bundle: PlatformAssetBundle#bb4b7(), devicePixelRatio: 2.6,
  I/flutter ( 1274):     locale: en_US, textDirection: TextDirection.ltr, platform: android)
  I/flutter ( 1274): This RenderObject had the following descendants (showing up to depth 5):
  I/flutter ( 1274):     child: RenderPadding#f05f1 relayoutBoundary=up6 NEEDS-PAINT
  I/flutter ( 1274):       child: RenderParagraph#4842a relayoutBoundary=up7 NEEDS-PAINT
  I/flutter ( 1274):         text: TextSpan
  
  </code></pre>
  
  <p>thanks for any help in advance</p>