ImageLoader shouldn't call confusingAndOftenMisusedAttached

What the ImageLoader really wants to know is whether it's appropriate to
fire events on its associated image elements. That's safe when the document is
active in a frame, which we can check more directly by asking whether the
document has an associated frame.

R=esprehn
BUG=299011

Review URL: https://chromiumcodereview.appspot.com/24972002

git-svn-id: svn://svn.chromium.org/blink/trunk@158517 bbb929c8-8fbe-4397-9dbb-9b2b20218538
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