Make dart:dom implementation types private so they don't muddle the docs.

client/dom/generated/src/frog/SVGMaskElement.dart

Index: client/dom/generated/src/frog/SVGMaskElement.dart
diff --git a/client/dom/generated/src/frog/SVGMaskElement.dart b/client/dom/generated/src/frog/SVGMaskElement.dart
index 41bea00df55851ad06255eae441768d7f753d370..2871ee6f42012efe70ddcb6c50c4730a3db2d36c 100644
--- a/client/dom/generated/src/frog/SVGMaskElement.dart
+++ b/client/dom/generated/src/frog/SVGMaskElement.dart
@@ -1,25 +1,25 @@
 
-class SVGMaskElementJs extends SVGElementJs implements SVGMaskElement native "*SVGMaskElement" {
+class _SVGMaskElementJs extends _SVGElementJs implements SVGMaskElement native "*SVGMaskElement" {
 
-  SVGAnimatedLengthJs get height() native "return this.height;";
+  _SVGAnimatedLengthJs get height() native "return this.height;";
 
-  SVGAnimatedEnumerationJs get maskContentUnits() native "return this.maskContentUnits;";
+  _SVGAnimatedEnumerationJs get maskContentUnits() native "return this.maskContentUnits;";
 
-  SVGAnimatedEnumerationJs get maskUnits() native "return this.maskUnits;";
+  _SVGAnimatedEnumerationJs get maskUnits() native "return this.maskUnits;";
 
-  SVGAnimatedLengthJs get width() native "return this.width;";
+  _SVGAnimatedLengthJs get width() native "return this.width;";
 
-  SVGAnimatedLengthJs get x() native "return this.x;";
+  _SVGAnimatedLengthJs get x() native "return this.x;";
 
-  SVGAnimatedLengthJs get y() native "return this.y;";
+  _SVGAnimatedLengthJs get y() native "return this.y;";
 
   // From SVGTests
 
-  SVGStringListJs get requiredExtensions() native "return this.requiredExtensions;";
+  _SVGStringListJs get requiredExtensions() native "return this.requiredExtensions;";
 
-  SVGStringListJs get requiredFeatures() native "return this.requiredFeatures;";
+  _SVGStringListJs get requiredFeatures() native "return this.requiredFeatures;";
 
-  SVGStringListJs get systemLanguage() native "return this.systemLanguage;";
+  _SVGStringListJs get systemLanguage() native "return this.systemLanguage;";
 
   bool hasExtension(String extension) native;
 
@@ -35,13 +35,13 @@ class SVGMaskElementJs extends SVGElementJs implements SVGMaskElement native "*S
 
   // From SVGExternalResourcesRequired
 
-  SVGAnimatedBooleanJs get externalResourcesRequired() native "return this.externalResourcesRequired;";
+  _SVGAnimatedBooleanJs get externalResourcesRequired() native "return this.externalResourcesRequired;";
 
   // From SVGStylable
 
-  SVGAnimatedStringJs get className() native "return this.className;";
+  _SVGAnimatedStringJs get className() native "return this.className;";
 
-  CSSStyleDeclarationJs get style() native "return this.style;";
+  _CSSStyleDeclarationJs get style() native "return this.style;";
 
-  CSSValueJs getPresentationAttribute(String name) native;
+  _CSSValueJs getPresentationAttribute(String name) native;
 }