This patch is the first part of using ShaderMap to contain shader
information in ProgramD3D, including the refactoring on struct
D3DUniform, D3DUniformBlock and ProgramD3DMetadata.

In the next patch all shader information in class ProgramD3D will
be organized in the form of ShaderMap.

BUG=angleproject:2169

Change-Id: I27008169dbf6cd8017a67f36f474667feddbd1f6
Reviewed-on: https://chromium-review.googlesource.com/1018728
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>