Remove pointer-to-int-cast suppression

Chrome now successfully builds with ToT Clang after
crrev/9243da16.

Bug: 1059231
Change-Id: I5208e0c6d5990146e28ef57617038430a4b3a310
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2095705
Auto-Submit: Arthur Eubanks <aeubanks@google.com>
Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#748662}

build/config/compiler/BUILD.gn

@@ -1539,13 +1539,6 @@ config("default_warnings") {
           # valid on Windows, which is LLP64.
           "-Wno-microsoft-cast",
         ]
-
-        if (llvm_force_head_revision && is_win) {
-          cflags += [
-            # TODO(https://crbug.com/1059231): Clean up, enable.
-            "-Wno-pointer-to-int-cast",
-          ]
-        }
       }
     }
   }