Revert of Turned on SkSL->GLSL compiler

src/sksl/ast/SkSLASTPrecision.h

-/*
- * Copyright 2016 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- 
-#ifndef SKSL_ASTPRECISION
-#define SKSL_ASTPRECISION
-
-#include "SkSLASTDeclaration.h"
-#include "../ir/SkSLModifiers.h"
-
-namespace SkSL {
-
-/**
- * Represents a precision declaration (e.g. 'precision mediump float;').
- */
-struct ASTPrecision : public ASTDeclaration {
-    // FIXME handle the type
-    ASTPrecision(Position position, Modifiers::Flag precision)
-    : INHERITED(position, kPrecision_Kind)
-    , fPrecision(precision) {}
-
-    std::string description() const {
-        switch (fPrecision) {
-            case Modifiers::kLowp_Flag: return "precision lowp float;";
-            case Modifiers::kMediump_Flag: return "precision mediump float;";
-            case Modifiers::kHighp_Flag: return "precision highp float;";
-            default: 
-                ASSERT(false); 
-                return "<error>";
-        }
-        ASSERT(false);
-        return "<error>";
-    }
-
-    const Modifiers::Flag fPrecision;
-
-    typedef ASTDeclaration INHERITED;
-};
-
-} // namespace
-
-#endif