Tweak asserts for dominant-baseline in SVGTextLayoutEngineBaseline

Tweak asserts for dominant-baseline in SVGTextLayoutEngineBaseline

The 'no-change' and 'reset-size' dominant-baseline value will consult
their parent to try and resolve a suitable value. If the parent has one
of these values, the process will continue up the ancestor chain.
When reaching the LayoutView however, we should encounter the initial
value ('auto') and the search will end.
Move the assertion for an existing parent down into the branches that
handle the values 'no-change' and 'reset-size'.
Also rewrap a comment and replace a FIXME with TODO.

BUG=534796
Committed: https://crrev.com/f733f40a85ce65d38260d88f12f20752bba70bb8
Cr-Commit-Position: refs/heads/master@{#350612}

[fs, 2015-09-24 16:21:45]

fs@opera.com changed reviewers:
+ pdr@chromium.org

[fs, 2015-09-24 16:21:45]

I noticed that these "problematic" values had been dropped from CSS Inline [1],
so maybe some form of use-countering could be in order here...

[1] https://drafts.csswg.org/css-inline/#dominant-baseline-property

[pdr., 2015-09-24 17:55:12]

LGTM

[pdr., 2015-09-24 17:55:14]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2015-09-24 17:56:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1360083003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1360083003/1

[commit-bot: I haz the power, 2015-09-24 18:38:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-24 18:40:12]

Patchset 1 (id:??) landed as
https://crrev.com/f733f40a85ce65d38260d88f12f20752bba70bb8
Cr-Commit-Position: refs/heads/master@{#350612}