Roll src/third_party/skia e471c05..20ebd0c (4 commits) (#7894)

https://skia.googlesource.com/skia.git/%2Blog/e471c05f92e8..20ebd0cb3882

git log e471c05..20ebd0c --date=short --no-merges --format=%ad %ae %s
2019-02-20 reed@google.com remove SK_SUPPORT_LEGACY_TEXTBLOBCACHEDIFFCANVAS_CONSTRUCTOR code
2019-02-20 fmalita@chromium.org [skottie] Tint effect support
2019-02-20 michaelludwig@google.com Support decal mode in GrTextureProducer
2019-02-20 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ../src bf1a36e53e69..dca111a7573e (503 commits)

The AutoRoll server is located here: https://autoroll.skia.org/r/skia-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff (jvanverth@google.com), and stop
the roller if necessary.

DEPS

@@ -23,7 +23,7 @@ vars = {
   'fuchsia_git': 'https://fuchsia.googlesource.com',
   'github_git': 'https://github.com',
   'skia_git': 'https://skia.googlesource.com',
-  'skia_revision': 'e471c05f92e86c8f8a460f55c775ca245924519e',
+  'skia_revision': '20ebd0cb3882d1bdeed04eaa983b0e5842f0fdaf',
 
   # When updating the Dart revision, ensure that all entries that are
   # dependencies of Dart are also updated to match the entries in the

ci/licenses_golden/licenses_skia

@@ -1,4 +1,4 @@
-Signature: b14d48e409320424ded40cdb1731a9a2
+Signature: 80158806ee7715512b12aa7651039efe
 
 UNUSED LICENSES:
 

sky/packages/sky_engine/LICENSE

@@ -2808,6 +2808,7 @@ THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 --------------------------------------------------------------------------------
 boringssl
+engine
 etc1
 observatory_pub_packages
 skia