Make angle::Result an enum.

This moves away from a class type to a value type. This should improve
performance when using angle::Result as a return value. Previously the
generated code would return a pointer instead of a value.

Improves performance in the most targeted microbenchmark by 10%. In
more realistic scanarios it will have a smaller improvement. Also
simplifies the class implementation and usage.

Includes some unrelated code generation changes.

Bug: angleproject:2491
Change-Id: Ifcf86870bf1c00a2f73c39ea6e4f05ca705050aa
Reviewed-on: https://chromium-review.googlesource.com/c/1356139
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/renderer_utils.cpp b/src/libANGLE/renderer/renderer_utils.cpp
index 14beeed..5eb2b06 100644
--- a/src/libANGLE/renderer/renderer_utils.cpp
+++ b/src/libANGLE/renderer/renderer_utils.cpp
@@ -414,7 +414,7 @@
     *textureOut = mIncompleteTextures[type].get();
     if (*textureOut != nullptr)
     {
-        return angle::Result::Continue();
+        return angle::Result::Continue;
     }
 
     ContextImpl *implFactory = context->getImplementation();
@@ -468,7 +468,7 @@
 
     mIncompleteTextures[type].set(context, t.release());
     *textureOut = mIncompleteTextures[type].get();
-    return angle::Result::Continue();
+    return angle::Result::Continue;
 }
 
 #define ANGLE_INSTANTIATE_SET_UNIFORM_MATRIX_FUNC(cols, rows)                            \
@@ -580,7 +580,7 @@
     ANGLE_CHECK_GL_MATH(contextImpl, startVertexInt64 <= std::numeric_limits<GLint>::max())
 
     *firstVertexOut = static_cast<GLint>(startVertexInt64);
-    return angle::Result::Continue();
+    return angle::Result::Continue;
 }
 
 angle::Result GetVertexRangeInfo(const gl::Context *context,
@@ -606,6 +606,6 @@
         *startVertexOut = firstVertex;
         *vertexCountOut = vertexOrIndexCount;
     }
-    return angle::Result::Continue();
+    return angle::Result::Continue;
 }
 }  // namespace rx