Revert of Move ScrollAnimatorTest.cpp to Source/platform/scroll/.

Revert of Move ScrollAnimatorTest.cpp to Source/platform/scroll/. (patchset #2 id:20001 of https://codereview.chromium.org/1438043011/ )

Reason for revert:
Fails on Oilpan (leaked mock object). Suspect an explicit GC is required.

https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Oilpan/builds/30981/steps/blink_platform_unittests/logs/ScrollAnimatorEnabled.Disabled

Original issue's description:
> Move ScrollAnimatorTest.cpp to Source/platform/scroll/.
>
> Some classes in these files were moved into anonymous namespaces, because
> otherwise they generated ODR violations by being linked into the same test
> binary. (And this manifested as a crash, rather than a compile failure!)
>
> BUG=353585
>
> Committed: https://crrev.com/0a6e1d78456bfaf594c236123081e5f3d457ed9c
> Cr-Commit-Position: refs/heads/master@{#359850}

TBR=mkwst@chromium.org,skobes@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=353585
Committed: https://crrev.com/45549784f2c6b8b94a9dfb9c572ea44654800611
Cr-Commit-Position: refs/heads/master@{#359861}

[jbroman, 2015-11-16 17:47:04]

Created Revert of Move ScrollAnimatorTest.cpp to Source/platform/scroll/.

[commit-bot: I haz the power, 2015-11-16 17:47:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1450953002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1450953002/1

[commit-bot: I haz the power, 2015-11-16 17:48:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-16 17:49:38]

Patchset 1 (id:??) landed as
https://crrev.com/45549784f2c6b8b94a9dfb9c572ea44654800611
Cr-Commit-Position: refs/heads/master@{#359861}