D3D: Update dynamic BufferUsage flags.

Changed the mapping between gl::BufferUsage flags
and D3DBufferUsage flags. Only gl::BufferUsage::DynamicDraw
gets mapped to D3DBufferUsage::DYNAMIC now. This reflects
a better mapping between GL and D3D.

BUG=angleproject:3366

Change-Id: I5062f91fdb3664339e2c259b399d5f47401675d6
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1569465
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>

AUTHORS

@@ -29,6 +29,7 @@ The Qt Company Ltd.
 Advanced Micro Devices, Inc.
 LG Electronics, Inc.
 IBM Inc.
+AdaptVis GmbH
 
 Jacek Caban
 Mark Callow

CONTRIBUTORS

@@ -141,3 +141,7 @@ LG Electronics, Inc.
 
 IBM Inc.
  Junliang Yan
+
+AdaptVis GmbH
+ Sascha Kolodzey
+

src/libANGLE/renderer/d3d/BufferD3D.cpp

@@ -54,16 +54,16 @@ void BufferD3D::updateD3DBufferUsage(const gl::Context *context, gl::BufferUsage
         case gl::BufferUsage::StaticCopy:
         case gl::BufferUsage::StaticDraw:
         case gl::BufferUsage::StaticRead:
-            mUsage = D3DBufferUsage::STATIC;
-            initializeStaticData(context);
-            break;
-
         case gl::BufferUsage::DynamicCopy:
-        case gl::BufferUsage::DynamicDraw:
         case gl::BufferUsage::DynamicRead:
         case gl::BufferUsage::StreamCopy:
         case gl::BufferUsage::StreamDraw:
         case gl::BufferUsage::StreamRead:
+            mUsage = D3DBufferUsage::STATIC;
+            initializeStaticData(context);
+            break;
+
+        case gl::BufferUsage::DynamicDraw:
             mUsage = D3DBufferUsage::DYNAMIC;
             break;
         default: