Revert "Fix and enable warning C4244 (Conversion from 'type1' to 'type2', possible loss of data)"

Causing a build failure on Mac/Clang:

./Tokenizer.cpp:551:7: error: extra tokens at end of #else directive [-Werror,-Wextra-tokens]
#else if defined(_MSC_VER)

http://build.chromium.org/p/chromium.gpu.fyi/builders/GPU%20Mac%20Builder/builds/29136

This reverts commit 3b26e231d99154814eb428f75a67bbe7a21adadc.

Change-Id: I2d11ddcc18130d908fd2ec3d6f5ab890cfccd5e7
Reviewed-on: https://chromium-review.googlesource.com/264983
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/d3d/VertexDataManager.cpp b/src/libANGLE/renderer/d3d/VertexDataManager.cpp
index 91770dc..cb70b9e 100644
--- a/src/libANGLE/renderer/d3d/VertexDataManager.cpp
+++ b/src/libANGLE/renderer/d3d/VertexDataManager.cpp
@@ -291,7 +291,7 @@
     if (directStorage)
     {
         outputElementSize = ComputeVertexAttributeStride(attrib);
-        streamOffset = static_cast<unsigned int>(attrib.offset + outputElementSize * firstVertexIndex);
+        streamOffset = attrib.offset + outputElementSize * firstVertexIndex;
     }
     else if (staticBuffer)
     {