GL back-end error refactor.

Adds explicit error handling to a few scoped state handler classes.
Otherwise mostly mechanical refactoring.

Bug: angleproject:2753
Change-Id: I2bf969a68f45880902b6e7902297c1340a76a1c4
Reviewed-on: https://chromium-review.googlesource.com/c/1255647
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/renderer/d3d/IndexBuffer.cpp b/src/libANGLE/renderer/d3d/IndexBuffer.cpp
index 565f730..1b52f64 100644
--- a/src/libANGLE/renderer/d3d/IndexBuffer.cpp
+++ b/src/libANGLE/renderer/d3d/IndexBuffer.cpp
@@ -75,9 +75,8 @@
 {
     // Protect against integer overflow
     bool check = (mWritePosition + size < mWritePosition);
-    ANGLE_CHECK_HR(GetImplAs<ContextD3D>(context), !check,
-                   "Mapping of internal index buffer would cause an integer overflow.",
-                   E_OUTOFMEMORY);
+    ANGLE_CHECK(GetImplAs<ContextD3D>(context), !check,
+                "Mapping of internal index buffer would cause an integer overflow.", E_OUTOFMEMORY);
 
     angle::Result error = mIndexBuffer->mapBuffer(context, mWritePosition, size, outMappedMemory);
     if (error == angle::Result::Stop())