Add dynamic declaration to CssRectangle width/height setters

tools/dom/src/CssRectangle.dart

Index: tools/dom/src/CssRectangle.dart
diff --git a/tools/dom/src/CssRectangle.dart b/tools/dom/src/CssRectangle.dart
index 7d8c84405a6f3fbc713dea9c69ded40351b6e2d0..90a433f5a5d0d94dfd17405ddb990d71c32af24c 100644
--- a/tools/dom/src/CssRectangle.dart
+++ b/tools/dom/src/CssRectangle.dart
@@ -26,7 +26,7 @@ class _ContentCssRect extends CssRect {
    * `height` function in jQuery and the calculated `height` CSS value,
    * converted to a num in pixels.
    */
-  set height(newHeight) {
+  set height(dynamic newHeight) {
     if (newHeight is Dimension) {
       if (newHeight.value < 0) newHeight = new Dimension.px(0);
       _element.style.height = newHeight.toString();
@@ -46,7 +46,7 @@ class _ContentCssRect extends CssRect {
    * and the calculated
    * `width` CSS value, converted to a dimensionless num in pixels.
    */
-  set width(newWidth) {
+  set width(dynamic newWidth) {
     if (newWidth is Dimension) {
       if (newWidth.value < 0) newWidth = new Dimension.px(0);
       _element.style.width = newWidth.toString();
@@ -206,7 +206,7 @@ abstract class CssRect implements Rectangle<num> {
    *
    * Note that only the content height can actually be set via this method.
    */
-  set height(newHeight) {
+  set height(dynamic newHeight) {
     throw new UnsupportedError("Can only set height for content rect.");
   }
 
@@ -220,7 +220,7 @@ abstract class CssRect implements Rectangle<num> {
    *
    * Note that only the content width can be set via this method.
    */
-  set width(newWidth) {
+  set width(dynamic newWidth) {
     throw new UnsupportedError("Can only set width for content rect.");
   }