SkPDF: Add Sfntly to DEPS, gyp

Note: this can be disabled via:
    GYP_DEFINES='skia_pdf_use_sfntly=0

Warning: dm is 34% slower and uses 9% more memory.  This is
okay.

Motivation: We want to test this code path in DM, since it is
always used by Chromium and Android.

BUG=skia:3563

Committed: https://skia.googlesource.com/skia/+/6a53b04e26749ea61f690ece408f2a1c0a5ad5bb

Review URL: https://codereview.chromium.org/1134683006
diff --git a/DEPS b/DEPS
index 549c1bf..aee9e05 100644
--- a/DEPS
+++ b/DEPS
@@ -30,6 +30,11 @@
 
   # The line below is needed for compiling SkV8Example. Do not delete.
   #"third_party/externals/v8": "https://chromium.googlesource.com/v8/v8.git@5f1ae66d5634e43563b2d25ea652dfb94c31a3b4",
+
+  # sfntly is used by the PDF backend for font subsetting
+  "third_party/externals/sfntly" : "https://chromium.googlesource.com/external/sfntly/cpp/src.git@1bdaae8fc788a5ac8936d68bf24f37d977a13dac",
+  # ICU is needed for sfntly.
+  "third_party/externals/icu" : "https://chromium.googlesource.com/chromium/deps/icu.git@ce41627e388fb46ab49671bd16a5db81dcd75a71",
 }
 
 recursedeps = [ "common" ]