display original message on xml syntax error

[1024]

The original error messagein the red box is ugly.

[1024]

WebKit adds parsererror element direct under the body (before svg) if the syntax was wrong.

So:

1. check existence of the parsererror
2. remove the element from DOM
3. parse the persererror
4. display it

[1024]

easier way to make error message pretty.

ref. objective c - WebView Local CSS - Stack Overflow

[1024]

Apply original style to parser error message (ref #21)

→ <<cset 2cfcaa52b47b>>

[1024]

Add error icon (ref #21)

→ <<cset 5b67a04cad2a>>

[1024]

I close this task because I believe the current implementation is enough.