Revert of Add libc++ __tree to ubsan blacklist. (patchset #2 id:20001 of...

Revert of Add libc++ __tree to ubsan blacklist. (patchset #2 id:20001 of https://codereview.chromium.org/2109663003/ )

Reason for revert:
Issued fixed upstream

Original issue's description:
> Add libc++ __tree to ubsan blacklist.
>
> libc++ __tree is not ubsan clean. It floods compile and run steps
> with "runtime error: downcast" and "runtime error: upcast" errors,
> making ubsan much less usable.
> This is a KI with libc++: https://llvm.org/bugs/show_bug.cgi?id=19302
>
> Committed: https://crrev.com/e2abe2366d707ac6ad308e2643f41423971f81fc
> Cr-Commit-Position: refs/heads/master@{#402902}

TBR=dpranke@chromium.org,ochang@chromium.org,thakis@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.

Review-Url: https://codereview.chromium.org/2983093003
Cr-Commit-Position: refs/heads/master@{#487986}

tools/ubsan/blacklist.txt

@@ -69,9 +69,3 @@ fun:*re2*RegexpD*
 #############################################################################
 # Harmless float division by zero.
 fun:*RendererFrameManager*CullUnlockedFrames*
-
-#############################################################################
-# libc++ __tree and map are not UBSAN clean
-# https://llvm.org/bugs/show_bug.cgi?id=19302
-src:*/third_party/libc\+\+/trunk/include/__tree
-src:*/third_party/libc\+\+/trunk/include/map