Remove ineffective UBSan suppression.

The issue was a general UBSan one, not a UBSan vptr issue. Also, we
didn't have to blacklist the false positive, but instead provided UBSan
wth the necessary type info.

BUG=737384

Change-Id: Ie6299e1edfc010ef976ab4fbefacba4d06e305b7
Reviewed-on: https://chromium-review.googlesource.com/579448Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Nicolas Capens <nicolascapens@google.com>
Cr-Commit-Position: refs/heads/master@{#488322}

tools/ubsan/vptr_blacklist.txt

@@ -99,7 +99,6 @@ src:*/third_party/libwebm/source/mkvmuxer.cpp
 #############################################################################
 # LLVM is not UBSan vptr clean.
 src:*third_party/swiftshader/third_party/LLVM*
-src:*third_party/swiftshader/third_party/llvm\-subzero*
 
 #############################################################################
 # UBSan yields false positives in SwiftShader's libEGL when objects created in