Revert of Turned on SkSL->GLSL compiler

src/sksl/SkSLParser.h

Index: src/sksl/SkSLParser.h
diff --git a/src/sksl/SkSLParser.h b/src/sksl/SkSLParser.h
index d1ae0d0e9f5d2f70883f751db151214322edf328..75f304bc8c5ccf7605b9967cb64318ceb3d1cc1c 100644
--- a/src/sksl/SkSLParser.h
+++ b/src/sksl/SkSLParser.h
@@ -35,7 +35,6 @@
 struct ASTLayout;
 struct ASTModifiers;
 struct ASTParameter;
-struct ASTPrecision;
 struct ASTReturnStatement;
 struct ASTStatement;
 struct ASTSuffix;
@@ -101,7 +100,7 @@
     // don't need to call any of these outside of the parser. The function declarations in the .cpp
     // file have comments describing the grammar rules.
 
-    std::unique_ptr<ASTDeclaration> precision();
+    void precision();
 
     std::unique_ptr<ASTDeclaration> directive();