D3D11: Don't use ErrorOrResult in TransformFeedback11.

src/libANGLE/renderer/d3d/d3d11/StateManager11.cpp

@@ -3329,7 +3329,7 @@ gl::Error StateManager11::syncTransformFeedbackBuffers(const gl::Context *contex
     }
 
     const std::vector<ID3D11Buffer *> *soBuffers = nullptr;
-    ANGLE_TRY_RESULT(tf11->getSOBuffers(context), soBuffers);
+    ANGLE_TRY(tf11->getSOBuffers(context, &soBuffers));
     const std::vector<UINT> &soOffsets = tf11->getSOBufferOffsets();
 
     deviceContext->SOSetTargets(tf11->getNumSOBuffers(), soBuffers->data(), soOffsets.data());

src/libANGLE/renderer/d3d/d3d11/TransformFeedback11.cpp

@@ -100,8 +100,8 @@ UINT TransformFeedback11::getNumSOBuffers() const
     return static_cast<UINT>(mBuffers.size());
 }
 
-gl::ErrorOrResult<const std::vector<ID3D11Buffer *> *> TransformFeedback11::getSOBuffers(
-    const gl::Context *context)
+gl::Error TransformFeedback11::getSOBuffers(const gl::Context *context,
+                                            const std::vector<ID3D11Buffer *> **buffersOut)
 {
     for (size_t bindingIdx = 0; bindingIdx < mBuffers.size(); bindingIdx++)
     {
@@ -114,7 +114,8 @@ gl::ErrorOrResult<const std::vector<ID3D11Buffer *> *> TransformFeedback11::getS
         }
     }
 
-    return &mBuffers;
+    *buffersOut = &mBuffers;
+    return gl::NoError();
 }
 
 const std::vector<UINT> &TransformFeedback11::getSOBufferOffsets() const

src/libANGLE/renderer/d3d/d3d11/TransformFeedback11.h

@@ -41,7 +41,8 @@ class TransformFeedback11 : public TransformFeedbackImpl
     bool isDirty() const;
 
     UINT getNumSOBuffers() const;
-    gl::ErrorOrResult<const std::vector<ID3D11Buffer *> *> getSOBuffers(const gl::Context *context);
+    gl::Error getSOBuffers(const gl::Context *context,
+                           const std::vector<ID3D11Buffer *> **buffersOut);
     const std::vector<UINT> &getSOBufferOffsets() const;
 
     Serial getSerial() const;