Specs: hit testing (and some cleanup)

sky/examples/style/toolbar-layout.sky

 SKY MODULE
 <import src="sky:core" as="sky"/>
 <script>
  // display: toolbar;
  // toolbar-spacing: <length>
  // display: spring; // remaining space is split equally amongst the springs
  // children are vertically centered, layout out left-to-right with toolbar-spacing space between them
  // last child is hidden by default unless there's not enough room for the others, then it's shown last, right-aligned
  module.exports.SpringLayoutManager = class SpringLayoutManager extends sky.LayoutManager { }
  sky.registerLayoutManager('spring', module.exports.SpringLayoutManager);
  sky.registerProperty({
    name: 'toolbar-spacing',
-   type: sky.LengthStyleValueType,
+   type: sky.PositiveLengthStyleValueType,
    inherits: true,
-   initialValue: { value: 8, unit: 'px' },
+   initialValue: 8,
    needsLayout: true,
  });
  module.exports.ToolbarLayoutManager = class ToolbarLayoutManager extends sky.LayoutManager {
    constructor (styleNode) {
      super(styleNode);
      this.showingOverflow = false;
      this.firstSkippedChild = null;
      this.overflowChild = null;
    }
    function layout(width, height) {
@@ skipping 98 matching lines @@
      else
        this.firstSkippedChild = this.overflowChild;
 
      return {
        width: width,
        height: height,
      }
    }
    function getIntrinsicWidth() {
      let width = this.node.getProperty('width');
-     if (typeof height != 'number') {
+     if (typeof width != 'number') {
        let spacing = this.node.getProperty('toolbar-spacing');
        if (typeof spacing != 'number')
          spacing = 0;
        width = 0;
        let children = this.walkChildren();
        let loop = children.next();
        // we exclude the last child because at our ideal width we wouldn't need it
        let last1 = null; // last one
        let last2 = null; // one before the last one
        while (!loop.done) {
@@ skipping 54 matching lines @@
          canvas.clip();
          child.paint(canvas);
        } finally {
          canvas.restore();
        }
      }
    }
  }
  sky.registerLayoutManager('toolbar', module.exports.ToolbarLayoutManager);
 </script>