[SVGDom] Add <circle>, <ellipse> support

BUILD.gn

 # Copyright 2016 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 declare_args() {
 }
 
 skia_public_includes = [
   "include/android",
@@ skipping 503 matching lines @@
     ":tool_utils",
   ]
 }
 
 test_lib("experimental_svg_model") {
   public_include_dirs = [ "experimental/svg/model" ]
   sources = [
     "experimental/svg/model/SkSVGAttribute.cpp",
     "experimental/svg/model/SkSVGAttributeParser.cpp",
     "experimental/svg/model/SkSVGContainer.cpp",
+    "experimental/svg/model/SkSVGCircle.cpp",
     "experimental/svg/model/SkSVGDOM.cpp",
+    "experimental/svg/model/SkSVGEllipse.cpp",
     "experimental/svg/model/SkSVGNode.cpp",
     "experimental/svg/model/SkSVGPath.cpp",
     "experimental/svg/model/SkSVGPoly.cpp",
     "experimental/svg/model/SkSVGRect.cpp",
     "experimental/svg/model/SkSVGRenderContext.cpp",
     "experimental/svg/model/SkSVGSVG.cpp",
     "experimental/svg/model/SkSVGShape.cpp",
     "experimental/svg/model/SkSVGTransformableNode.cpp",
     "experimental/svg/model/SkSVGValue.cpp",
   ]
@@ skipping 56 matching lines @@
       "tools/SkShaper_harfbuzz.cpp",
       "tools/using_skia_and_harfbuzz.cpp",
     ]
     deps = [
       ":skia",
       "//third_party/harfbuzz",
     ]
     testonly = true
   }
 }