Cleanup SVGElement::isInUserAgentShadowTree and rename it inUseShadowTree

This patch renames isInUserAgentShadowTree to inUseShadowTree and
cleans up the implementation to check whether an SVGElement is in
a <use>-created shadow tree. This patch also cleans up the
remaining callers of inShadowTree() to call inUseShadowTree(), as
many of the comments suggest.

No change in behavior because we don't have SVG in user agent
shadow roots.

BUG=364302

Review URL: https://codereview.chromium.org/238293009

git-svn-id: svn://svn.chromium.org/blink/trunk@171904 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove some dead code from css/ folder

Remove some dead code from css/ folder. Several methods / members were defined
but never used.

R=ojan@chromium.org,jchaffraix@chromium.org

Review URL: https://codereview.chromium.org/241363003

git-svn-id: svn://svn.chromium.org/blink/trunk@171905 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Iterate Through Fewer Children When Seeking Overhanging Floats

If a container's height is reduced it doesn't need to iterate through all
its children looking for floats that might now overhang - it only needs to
look back through float-containing children and even then only as far as the last
child with a float in its list of own/intruding floats that overhangs
the container's new height.

We also don't need to track the bottom position of the lowest hanging float
we encounter; we get that for free when we look at the lowestFloatLogicalBottom()
of the last child. This is so because each child keeps a copy of any
floats intruding from the previous sibling in its float list.

Review URL: https://codereview.chromium.org/228663014

git-svn-id: svn://svn.chromium.org/blink/trunk@171906 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Partial revert of r170233

This CL triggered a crash on this line of code. The comment at the top of the
function gives some hints as to why, but I wasn't able to construct a test
case that actually hits this code.

BUG=359547

Review URL: https://codereview.chromium.org/239393005

git-svn-id: svn://svn.chromium.org/blink/trunk@171907 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Suppress layer creation for descendants of GPU-rasterized layers

This suppresses layer creation in descendants (in stacking
order) of layers that are compositing for GPU-rasterization
hints. More specifically, compositing for animations and for
will-change is suppressed in these layers.

BUG=313532

Review URL: https://codereview.chromium.org/233063004

git-svn-id: svn://svn.chromium.org/blink/trunk@171908 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Use treescope for filter id references

This patch fixes a bug where ReferenceFilterBuilder used the document
to lookup id references instead of the element's treescope. This fixes
filters that appear in shadow trees and is the last document-based
getElementId call in the SVG codebase.

BUG=364358

Review URL: https://codereview.chromium.org/240333008

git-svn-id: svn://svn.chromium.org/blink/trunk@171909 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Simplify assert using DocumentLifecycle

BUG=358674

Review URL: https://codereview.chromium.org/232543002

git-svn-id: svn://svn.chromium.org/blink/trunk@171910 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[FastTextAutosizer] Do not inflate potential clusters in inflateTable

This patch changes inflateTable to not pre-inflate potential clusters.
This fixes a bug where inline block elements would appear too wide
because they were incorrectly pre-inflated in inflateTable. To
achieve this, blockMightBecomeCluster has been factored out and
is now shared by inflateTable and clusterHasEnoughTextToAutosize.

Before: http://pr.gg/wrapbefore.png
After: http://pr.gg/wrapafter.png

This patch also removes the unused function isLayoutRoot.

BUG=363893

Review URL: https://codereview.chromium.org/240443004

git-svn-id: svn://svn.chromium.org/blink/trunk@171911 bbb929c8-8fbe-4397-9dbb-9b2b20218538