Cosmetic change to base class lists.

We have inconsistent style for multiple-line base class list.

A) 37 instances

class Foo
    : public BaseA
    , public BaseB
    , public BaseC {
    ...

B) 17 instances

class Foo :
    public BaseA,
    public BaseB,
    public BaseC {
    ....

The number of A is larger than the number of B, and A is consistent with the
initialization list style. This CL changes B to A.

BUG=

Review URL: https://codereview.chromium.org/423803002

git-svn-id: svn://svn.chromium.org/blink/trunk@179018 bbb929c8-8fbe-4397-9dbb-9b2b20218538