Code refactoring for angle::BitSet and EXPECT_GL_TRUE/FALSE.

This change refactors two style issues to make it be consistent.
1) This CL uses "using" to replace "typedef" for all angle::BitSet<...>.
2) This CL uses EXPECT_GL_TRUE/FALSE to replace EXPECT_EQ for bool comparison.

BUG=angleproject:2005

Change-Id: I4afad92313ea2457bbfedf80f917a5873d7f29ee
Reviewed-on: https://chromium-review.googlesource.com/795871
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/Framebuffer.h b/src/libANGLE/Framebuffer.h
index 70223f0..cd1b28b 100644
--- a/src/libANGLE/Framebuffer.h
+++ b/src/libANGLE/Framebuffer.h
@@ -295,7 +295,7 @@
         DIRTY_BIT_MAX = DIRTY_BIT_UNKNOWN
     };
 
-    typedef angle::BitSet<DIRTY_BIT_MAX> DirtyBits;
+    using DirtyBits = angle::BitSet<DIRTY_BIT_MAX>;
     bool hasAnyDirtyBit() const { return mDirtyBits.any(); }
 
     void syncState(const Context *context);