Turned on SkSL->GLSL compiler
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2288033003

Committed: https://skia.googlesource.com/skia/+/9b0fe3d125f237d9884732a48414fa85fc71b4e3
Committed: https://skia.googlesource.com/skia/+/b12b3c6908c62c908b3680be01e3b5bfd30de310
Committed: https://skia.googlesource.com/skia/+/f008b0a59f45c0d4bea3e66faf3b01805009ec89
Committed: https://skia.googlesource.com/skia/+/08b2ccf398e2b81bc05d2c105837e5419899469b
Committed: https://skia.googlesource.com/skia/+/dcfe6dba4a335e50e86ff68e3252065d4197432c
Committed: https://skia.googlesource.com/skia/+/ccb1dd8f267f9d7fe7c9d0ce222ebc81b41853b3
Review-Url: https://codereview.chromium.org/2288033003
diff --git a/src/sksl/sksl_frag.include b/src/sksl/sksl_frag.include
index 123c339..98dbc90 100644
--- a/src/sksl/sksl_frag.include
+++ b/src/sksl/sksl_frag.include
@@ -4,5 +4,17 @@
 
 layout(builtin=15) in vec4 gl_FragCoord;
 
-)
+// 9999 is a temporary value that causes us to ignore these declarations beyond
+// adding them to the symbol table. This works fine in GLSL (where they do not
+// require any further handling) but will fail in SPIR-V. We'll have a better
+// solution for this soon.
+layout(builtin=9999) vec4 gl_LastFragData[1];
+layout(builtin=9999) vec4 gl_LastFragColor;
+layout(builtin=9999) vec4 gl_LastFragColorARM;
+layout(builtin=9999) int gl_SampleMaskIn[];
+layout(builtin=9999) out int gl_SampleMask[];
+layout(builtin=9999) vec4 gl_SecondaryFragColorEXT;
 
+layout(location=0,index=0,builtin=10001) out vec4 sk_FragColor;
+
+)