remove font from isSVG detection to avoid issues with legacy markup using the tag in HTML (close vuejs#4459)

Author: yyx990803

src/platforms/web/util/element.js

@@ -26,7 +26,7 @@ export const isHTMLTag = makeMap(
 // this map is intentionally selective, only covering SVG elements that may
 // contain child elements.
 export const isSVG = makeMap(
-  'svg,animate,circle,clippath,cursor,defs,desc,ellipse,filter,font,' +
+  'svg,animate,circle,clippath,cursor,defs,desc,ellipse,filter,' +
   'font-face,g,glyph,image,line,marker,mask,missing-glyph,path,pattern,' +
   'polygon,polyline,rect,switch,symbol,text,textpath,tspan,use,view',
   true