Fix alertserver imports

These have apparently changed.

TBR=jcgregorio
BUG=skia:3143

Review URL: https://codereview.chromium.org/715383004
Support for real fonts in skfiddle.

This CL uses a recently added configuration variable to cause skia's
custom font manager.  to cache the streams for all found fonts on the
system.  This way the fiddle won't try to open files on demand and
violate the security jail.

BUG=skia:
R=jcgregorio@google.com

Review URL: https://codereview.chromium.org/735343002
build release_developer, not release.

BUG=skia:

Review URL: https://codereview.chromium.org/739983002
logserver: Start a goroutine that uses the DefaultRegistry

logserver stopped reporting metrics to InfluxDB because common.InitWithMetrics
used its own registry where the logserver used DefaultRegistry.

BUG=skia:3132

Review URL: https://codereview.chromium.org/743483006
Add mergedtiles for calculating and caching merged Tiles.

Also update the description of TileStore.Get() to clarify what happens when you request a tile that doesn't exist.

And clean up some t.Skip()'s in filestore_test.go. Eeek.

BUG=skia:

Review URL: https://codereview.chromium.org/738573003
No longer need to run record_wpr with sudo