fix for ISSUE #7: empty canvas no longer stripped

Author: dontcallmedom

src/parser.c

@@ -284,6 +284,11 @@ static Bool CanPrune( TidyDocImpl* doc, Node *element )
     if (nodeIsTEXTAREA(element))
         return no;
 
+    /* fix for ISSUE #7 https://github.com/w3c/tidy-html5/issues/7 */
+    if (nodeIsCANVAS(element))
+        return no;
+
+
     if ( attrGetID(element) || attrGetNAME(element) )
         return no;
 

src/tags.h

@@ -230,6 +230,6 @@ uint TY_(nodeHeaderLevel)( Node* node );  /* 1, 2, ..., 6 */
 #define nodeIsU( node )          TagIsId( node, TidyTag_U )
 #define nodeIsMENU( node )       TagIsId( node, TidyTag_MENU )
 #define nodeIsBUTTON( node )     TagIsId( node, TidyTag_BUTTON )
-
+#define nodeIsCANVAS( node )     TagIsId( node, TidyTag_CANVAS )
 
 #endif /* __TAGS_H__ */