Move TF Feedback linked varyings into D3D-only.

The LinkedVarying structure is a D3D-specific type, and the GL
back-end doesn't need the extra info. Isolate this into the D3D
back-end so we can clean up the Impl inteface.

BUG=angleproject:1123

Change-Id: I76d77ac505876d865e3e02f47acbfd6665a9507e
Reviewed-on: https://chromium-review.googlesource.com/293764
Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/libANGLE/renderer/ProgramImpl.h b/src/libANGLE/renderer/ProgramImpl.h
index 4ba13c4..92d3868 100644
--- a/src/libANGLE/renderer/ProgramImpl.h
+++ b/src/libANGLE/renderer/ProgramImpl.h
@@ -43,9 +43,11 @@
     virtual LinkResult load(gl::InfoLog &infoLog, gl::BinaryInputStream *stream) = 0;
     virtual gl::Error save(gl::BinaryOutputStream *stream) = 0;
 
-    virtual LinkResult link(const gl::Data &data, gl::InfoLog &infoLog,
-                            gl::Shader *fragmentShader, gl::Shader *vertexShader,
-                            int *registers, std::vector<gl::LinkedVarying> *linkedVaryings,
+    virtual LinkResult link(const gl::Data &data,
+                            gl::InfoLog &infoLog,
+                            gl::Shader *fragmentShader,
+                            gl::Shader *vertexShader,
+                            int *registers,
                             std::map<int, gl::VariableLocation> *outputVariables) = 0;
 
     virtual void bindAttributeLocation(GLuint index, const std::string &name) = 0;
@@ -92,14 +94,12 @@
     const std::vector<gl::LinkedUniform*> &getUniforms() const { return mUniforms; }
     const std::map<GLuint, gl::VariableLocation> &getUniformIndices() const { return mUniformIndex; }
     const std::vector<gl::UniformBlock*> &getUniformBlocks() const { return mUniformBlocks; }
-    const std::vector<gl::LinkedVarying> &getTransformFeedbackLinkedVaryings() const { return mTransformFeedbackLinkedVaryings; }
     const std::vector<sh::Attribute> getShaderAttributes() { return mShaderAttributes; }
     const SemanticIndexArray &getSemanticIndexes() const { return mSemanticIndex; }
 
     std::vector<gl::LinkedUniform*> &getUniforms() { return mUniforms; }
     std::map<GLuint, gl::VariableLocation> &getUniformIndices() { return mUniformIndex; }
     std::vector<gl::UniformBlock*> &getUniformBlocks() { return mUniformBlocks; }
-    std::vector<gl::LinkedVarying> &getTransformFeedbackLinkedVaryings() { return mTransformFeedbackLinkedVaryings; }
     SemanticIndexArray &getSemanticIndexes() { return mSemanticIndex; }
 
     gl::LinkedUniform *getUniformByLocation(GLint location) const;
@@ -124,7 +124,6 @@
     std::map<GLuint, gl::VariableLocation> mUniformIndex;
 
     std::vector<gl::UniformBlock*> mUniformBlocks;
-    std::vector<gl::LinkedVarying> mTransformFeedbackLinkedVaryings;
 
     SemanticIndexArray mSemanticIndex;