Make default constructor of Font class to initialize all member variables

This patch makes default constructor of |Font| class to initialize
|m_canShapeWordByWord| and |m_shapeWordByWordComputed| member variables to
make MSAN happy.

This patch is a preparation of re-landing http://crrev.com/2082893005, which
is revered by uninitialized member variables of |Font|.

BUG=618237, 622566
TEST=n/a; MSAN will check this

Review-Url: https://codereview.chromium.org/2091633002
Cr-Commit-Position: refs/heads/master@{#401567}
(cherry picked from commit 2217e8c563575ead5c9450408529340ec93ccef7)

Review URL: https://codereview.chromium.org/2151143002 .

Cr-Commit-Position: refs/branch-heads/2743@{#640}
Cr-Branched-From: 2b3ae3b8090361f8af5a611712fc1a5ab2de53cb-refs/heads/master@{#394939}
1 file changed