RFR (S): 8189797:Fix initializer lists in G1ConcurrentMark and G1CMTask

[Kim Barrett]

> On Oct 23, 2017, at 12:50 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
> When there's an initializer list, especially a long one like this, I
> like to put the opening brace for the constructor body at the
> beginning of its own line, in order to make it easier to spot where
> the initializer list ends and the constructor body begins.

I forgot that for G1CMTask you moved the colon indicating the start of
the initializer list, but then left the indentation of the initializer
list unchanged, making it now inconsistent with others, including
G1ConcurrentMark in the same file.

I used to use the before-change style of G1CMTask (which makes the
initialier list to constructor body transition more obvious), but
changed to using always-cuddled ":" because that was more consistent
with other code I was seeing in Hotspot.