Improve the RenderObject.toString() logic so that there's not blank lines...

Improve the RenderObject.toString() logic so that there's not blank lines everywhere and to generally be better.
Adds sizes, positions, transforms, improves RenderParagraph's output.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1160233004

examples/stocks2/lib/stock_app.dart

@@ -218,5 +218,9 @@ class StocksApp extends App {
 
 void main() {
   print("starting stocks app!");
-  new StocksApp();
+  App app = new StocksApp();
+  app.appView.onFrame = () {
+    // uncomment this for debugging:
+    // app.appView.debugDumpRenderTree();
+  };
 }