https://bugs.webkit.org/show_bug.cgi?id=114402

Source/WebCore:

Reviewed by Dirk Schulze.

The firstIncludedIntervalLogicalTop() method's implementation relied on optimistic
assumptions about floating point accuracy which, in rare cases, caused it to discard
first-fit locations based on the intersection of the minLogicalIntervalTop offset edge
and a polygon offset edge. Now: we do not verify that first-fit locations based on the
intersection of an offset edge and the minLogicalIntervalTop offset edge are below
the horizontal minLogicalIntervalTop line. They're essentially below the line "by definition".

Test: fast/exclusions/shape-inside/shape-inside-polygon-layout.html

* rendering/ExclusionPolygon.cpp:
(WebCore::ExclusionPolygon::firstIncludedIntervalLogicalTop): Avoid floating point problems
    when checking intersections with the offset edge based on minLogicalIntervalTop.
* rendering/ExclusionPolygon.h:
(WebCore::OffsetPolygonEdge::OffsetPolygonEdge): Initialize the basis field.
(WebCore::OffsetPolygonEdge::basis): Report what the offset edge is "based on": a polygon
    edge, the top of the line, or a (reflex) vertex.
(OffsetPolygonEdge): Added the Basis enum to enable tracking what the geometry of
    an offset edge is based on.

LayoutTests:

Verify that subsequent polygon shape-inside lines are vertically adjacent.

Reviewed by Dirk Schulze.

* fast/exclusions/shape-inside/shape-inside-polygon-layout-expected.txt: Added.
* fast/exclusions/shape-inside/shape-inside-polygon-layout.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148582 268f45cc-cd09-0410-ab3c-d52691b4dbfc