Display property as specified on svg elements.

The computed display of svg elements should be as for other elements. For
svg:svg elements, they should behave as other replaced elements when styled
with inline-block, table-cell, etc. For svg elements inside the root svg
element, they still get a computed value for display as other elements,
although the rendering is the same for all display values different from
'none'.

This change aligns the behavior with that of Gecko.

This change makes it possible to remove the custom style building for
display.

R=pdr@chromium.org,fs@opera.com
BUG=391959

Review URL: https://codereview.chromium.org/379463002

git-svn-id: svn://svn.chromium.org/blink/trunk@177649 bbb929c8-8fbe-4397-9dbb-9b2b20218538