incomplete inline markup within table cell generates malformed html

[Jun Omae]

(originally reported at ​th:#13959)

>>> import trac
>>> trac.__version__
'1.4.2'
>>> from trac.mimeview.api import RenderingContext
>>> from trac.resource import Resource
>>> from trac.test import EnvironmentStub
>>> from trac.test import MockRequest
>>> from trac.wiki.formatter import Formatter, format_to_html
>>> resource = Resource('wiki', 'WikiStart')
>>> env = EnvironmentStub()
>>> req = MockRequest(env)
>>> context = RenderingContext(resource, req.href, req.perm)
>>> context.req = req
>>> print(format_to_html(env, context, '|| text^1 ||'))
<table class="wiki">
<tr><td> text<sup>1
</td></tr></table>
</sup>
>>> print(format_to_html(env, context, '|| text^1^ ||'))
<table class="wiki">
<tr><td> text<sup>1</sup>
</td></tr></table>

>>> print(format_to_html(env, context, '|| text**1 ||'))
<table class="wiki">
<tr><td> text<strong>1
</td></tr></table>
</strong>
>>> print(format_to_html(env, context, '|| text**1** ||'))
<table class="wiki">
<tr><td> text<strong>1</strong>
</td></tr></table>

>>>