Rewrite BorderImageLength to not use the Relative length type

Rewrite BorderImageLength to not use the Relative length type

Remove the last remaining Relative length and instead store a Length
_and_ a double value along with a type tag, a pattern also used by
GridLength in the Flexbox code. While it increases memory usage
slightly, getting rid of the Relative length type is deemed more
important.

BUG=259107
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=161802

[Julien - ping for review, 2013-11-04 18:30:25]

lgtm

https://codereview.chromium.org/55833002/diff/40001/Source/platform/BorderIma...
File Source/platform/BorderImageLength.h (right):

https://codereview.chromium.org/55833002/diff/40001/Source/platform/BorderIma...
Source/platform/BorderImageLength.h:40: // Default is 'auto'
Default _Length_ is 'auto' if that changed, this wouldn't hold. We can either
make it obvious by calling Length(Auto) (which would be my preference) or
referencing this Length constructor here.

https://codereview.chromium.org/55833002/diff/40001/Source/platform/BorderIma...
Source/platform/BorderImageLength.h:71: return m_length == o.m_length &&
m_number == o.m_number && m_type == o.m_type;
Nit: Let's put m_type first. And |o| -> |other| ^_^

[davve, 2013-11-10 19:21:46]

Depends on https://codereview.chromium.org/55813002/

[commit-bot: I haz the power, 2013-11-11 11:50:08]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/davve@opera.com/55833002/100001

[commit-bot: I haz the power, 2013-11-12 11:37:23]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/davve@opera.com/55833002/100001

[commit-bot: I haz the power, 2013-11-12 12:22:31]

Change committed as 161802