Overload FloatLineLayoutUnit operators.
Overload FloatLineLayoutUnit operators.

FloatLineLayoutUnit is a transitional type
to help switch from float to LayoutUnit in
the LineBox class hierarchy.

In this CL, we add a bunch of overloaded
operators to the transitional class so that
when we flip the alias over to use this type,
the compiler knows how to interact with floats,
ints, LayoutUnits, etc.

This is part of step 2 of
https://docs.google.com/a/chromium.org/document/d/1fro9Drq78rYBwr6K9CPK-y0TDSVxlBuXl6A54XnKAyE/edit?usp=sharing

BUG=321237

Review URL: https://codereview.chromium.org/738203002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@186854 bbb929c8-8fbe-4397-9dbb-9b2b20218538

XiaosongWei/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,modulexcite/blink,smishenk/blink-crosswalk,kurli/blink-crosswalk,jtg-gg/blink,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,Bysmyyr/blink-crosswalk,nwjs/blink,smishenk/blink-crosswalk,nwjs/blink,jtg-gg/blink,PeterWangIntel/blink-crosswalk,XiaosongWei/blink-crosswalk,XiaosongWei/blink-crosswalk,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,jtg-gg/blink,jtg-gg/blink,jtg-gg/blink,modulexcite/blink,modulexcite/blink,nwjs/blink,XiaosongWei/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,kurli/blink-crosswalk,jtg-gg/blink,PeterWangIntel/blink-crosswalk,jtg-gg/blink,modulexcite/blink,kurli/blink-crosswalk,modulexcite/blink,Pluto-tv/blink-crosswalk,kurli/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,kurli/blink-crosswalk,smishenk/blink-crosswalk,Bysmyyr/blink-crosswalk,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,Bysmyyr/blink-crosswalk,Pluto-tv/blink-crosswalk,jtg-gg/blink,Bysmyyr/blink-crosswalk,jtg-gg/blink,modulexcite/blink,Pluto-tv/blink-crosswalk,jtg-gg/blink,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,nwjs/blink,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,modulexcite/blink,nwjs/blink,PeterWangIntel/blink-crosswalk,kurli/blink-crosswalk,nwjs/blink,modulexcite/blink,nwjs/blink,nwjs/blink,smishenk/blink-crosswalk,kurli/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,nwjs/blink,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,modulexcite/blink,modulexcite/blink,Bysmyyr/blink-crosswalk,Pluto-tv/blink-crosswalk,nwjs/blink