DevTools: [Documentation] Fix bugs of WikiParser.

WikiParser doesn't work right in cases of meeting opening brackets ([ or [[) and tables ({{{!}}). 

BUG=391593

Review URL: https://codereview.chromium.org/561233003

git-svn-id: svn://svn.chromium.org/blink/trunk@182150 bbb929c8-8fbe-4397-9dbb-9b2b20218538