Add new GM to stress test the GPU font cache for cases similar to

gyp/gmslides.gypi

 # include this gypi to include all the golden master slides.
 {
   'sources': [
     '../gm/aaclip.cpp',
     '../gm/aarectmodes.cpp',
     '../gm/alphagradients.cpp',
     '../gm/androidfallback.cpp',
     '../gm/arcofzorro.cpp',
     '../gm/arithmode.cpp',
     '../gm/beziereffects.cpp',
@@ skipping 36 matching lines @@
     '../gm/downsamplebitmap.cpp',
     '../gm/drawbitmaprect.cpp',
     '../gm/drawlooper.cpp',
     '../gm/extractbitmap.cpp',
     '../gm/emptypath.cpp',
     '../gm/fatpathfill.cpp',
     '../gm/factory.cpp',
     '../gm/filltypes.cpp',
     '../gm/filltypespersp.cpp',
     '../gm/filterbitmap.cpp',
+    '../gm/fontcache.cpp',
     '../gm/fontmgr.cpp',
     '../gm/fontscaler.cpp',
     '../gm/gammatext.cpp',
     '../gm/getpostextpath.cpp',
     '../gm/giantbitmap.cpp',
     '../gm/gradients.cpp',
     '../gm/gradients_no_texture.cpp',
     '../gm/gradientDirtyLaundry.cpp',
     '../gm/gradient_matrix.cpp',
     '../gm/gradtext.cpp',
@@ skipping 75 matching lines @@
     '../gm/xfermodes2.cpp',
     '../gm/xfermodes3.cpp',
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: