Add dummy dart:html library for documentation.

lib/html/doc/interface/SVGRect.dartdoc

Index: lib/html/doc/interface/SVGRect.dartdoc
diff --git a/lib/html/doc/interface/SVGRect.dartdoc b/lib/html/doc/interface/SVGRect.dartdoc
new file mode 100644
index 0000000000000000000000000000000000000000..28212d16a9ce68d8f2104afe04d19dd6fd94768b
--- /dev/null
+++ b/lib/html/doc/interface/SVGRect.dartdoc
@@ -0,0 +1,23 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// WARNING:
+//   This file contains documentation that is merged into the real source.
+//   Do not make code changes here.
+
+/// @domName SVGRect
+interface SVGRect {
+
+  /** @domName SVGRect.height */
+  num height;
+
+  /** @domName SVGRect.width */
+  num width;
+
+  /** @domName SVGRect.x */
+  num x;
+
+  /** @domName SVGRect.y */
+  num y;
+}