Prepare to move core/platform/text into blink_platform.dll

This CL moves NotImplemented, Logging, Language, and DateComponents into
blink_platform.dll because core/platform/text depends on this code. After this
CL lands, we'll be ready to move the bulk of core/platform/text into
blink_platform.dll.

In order to move this code into the DLL, I had to change how blink_common.dll
works a bit. Instead of being defined in web.gyp, I've moved the definition to
blink_platform.gyp to avoid a circular GYP dependency (because web.gyp depends
on blink_platform.gyp). This change makes sense because blink_common.dll is
really a tiny sliver of blink_platform.dll that's needed in the browser process
on Windows. To maintain sanity, I've also moved the source files for
blink_common.dll into Source/platform.

BUG=297477
R=jamesr

Review URL: https://chromiumcodereview.appspot.com/25195003

git-svn-id: svn://svn.chromium.org/blink/trunk@158518 bbb929c8-8fbe-4397-9dbb-9b2b20218538