Remove layout(marker) from runtime effect SkSL

This is another strange, experimental feature that clutters the
implementation and isn't used by anyone (to my knowledge).

Change-Id: I538b7eca0cd28aab32f4739b23459731ade9105e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/398226
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
diff --git a/src/sksl/codegen/SkSLSPIRVCodeGenerator.cpp b/src/sksl/codegen/SkSLSPIRVCodeGenerator.cpp
index c00ef53..46d1515 100644
--- a/src/sksl/codegen/SkSLSPIRVCodeGenerator.cpp
+++ b/src/sksl/codegen/SkSLSPIRVCodeGenerator.cpp
@@ -2053,8 +2053,7 @@
                                          /*binding=*/-1, /*index=*/-1, /*set=*/-1, /*builtin=*/-1,
                                          /*inputAttachmentIndex=*/-1,
                                          Layout::kUnspecified_Primitive, /*maxVertices=*/1,
-                                         /*invocations=*/-1, /*marker=*/"", /*when=*/"",
-                                         Layout::CType::kDefault),
+                                         /*invocations=*/-1, /*when=*/"", Layout::CType::kDefault),
                                   /*flags=*/0),
                         SKSL_RTHEIGHT_NAME, fContext.fTypes.fFloat.get());
                 StringFragment name("sksl_synthetic_uniforms");
@@ -2074,7 +2073,7 @@
                         Layout(flags, /*location=*/-1, /*offset=*/-1, binding, /*index=*/-1,
                                set, /*builtin=*/-1, /*inputAttachmentIndex=*/-1,
                                Layout::kUnspecified_Primitive,
-                               /*maxVertices=*/-1, /*invocations=*/-1, /*marker=*/"", /*when=*/"",
+                               /*maxVertices=*/-1, /*invocations=*/-1, /*when=*/"",
                                Layout::CType::kDefault),
                         Modifiers::kUniform_Flag);
                 const Variable* intfVar = fSynthetics.takeOwnershipOfSymbol(