Declare and forward dependency on blink_platform

blink_platform's GraphicsTypes3D.h includes headers from khronos that
in our build system require having the include paths from the
khronos_headers target in the build line for every target that includes
GraphicsTypes3D.h. This declares the dependency on blink_platform in
targets that use it and forwards dependent settings in targets that
expose public headers that include GraphicsTypes3D.h so they can pick
up the include paths without needing an all_dependent_settings in
khronos_headers.

Review URL: https://codereview.chromium.org/481123002

git-svn-id: svn://svn.chromium.org/blink/trunk@180499 bbb929c8-8fbe-4397-9dbb-9b2b20218538