Add support for multiple frames in SkCodec

tests/CodecTest.cpp

Index: tests/CodecTest.cpp
diff --git a/tests/CodecTest.cpp b/tests/CodecTest.cpp
index 32482413f11d65da9723b90135d99b7599465685..5f9130070a0e58a138d89ad32fc8f7019c606928 100644
--- a/tests/CodecTest.cpp
+++ b/tests/CodecTest.cpp
@@ -470,10 +470,10 @@ DEF_TEST(Codec, r) {
 
     // GIF
     // FIXME: We are not ready to test incomplete GIFs
-    check(r, "box.gif", SkISize::Make(200, 55), true, false, false);
-    check(r, "color_wheel.gif", SkISize::Make(128, 128), true, false, false);
+    check(r, "box.gif", SkISize::Make(200, 55), false, false, false);
+    check(r, "color_wheel.gif", SkISize::Make(128, 128), false, false, false);
     // randPixels.gif is too small to test incomplete
-    check(r, "randPixels.gif", SkISize::Make(8, 8), true, false, false);
+    check(r, "randPixels.gif", SkISize::Make(8, 8), false, false, false);
 
     // JPG
     check(r, "CMYK.jpg", SkISize::Make(642, 516), true, false, true);
@@ -1266,7 +1266,8 @@ DEF_TEST(Codec_fallBack, r) {
 
     // Formats that currently do not support incremental decoding
     auto files = {
-            "box.gif",
+            // FIXME: box.gif does not currently support either.
+            // "box.gif",
             "CMYK.jpg",
             "color_wheel.ico",
             "mandrill.wbmp",