Docs: fix the hitTest() logic for display:toolbar since it doesn't use size 0x0 for its hidden chil…

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);
@@ skipping 186 matching lines @@
    }
    function hitTest(x, y) {
      let children = this.walkChildrenBackwards();
      let loop = children.next();
      while ((!loop.done) && (loop.value != this.firstSkippedChild))
        if (this.inChild(loop.value, x, y))
          return loop.value;
      if (this.showingOverflow)
        if (this.inChild(this.overflowChild, x, y))
          return this.overflowChild;
+     return this.node;
    }
  }
  sky.registerLayoutManager('toolbar', module.exports.ToolbarLayoutManager);
 </script>