Revert of Clang plugin to check that unstable types are not used in IPC.

tools/clang/plugins/FindBadConstructsAction.cpp

Index: tools/clang/plugins/FindBadConstructsAction.cpp
diff --git a/tools/clang/plugins/FindBadConstructsAction.cpp b/tools/clang/plugins/FindBadConstructsAction.cpp
index f857ac2bbe88810b440bab4a0af02bba26773705..ad9fc5582638b91b8a8aec329d4b8b1cc6b2ce23 100644
--- a/tools/clang/plugins/FindBadConstructsAction.cpp
+++ b/tools/clang/plugins/FindBadConstructsAction.cpp
@@ -21,7 +21,7 @@
       : visitor_(*instance, options) {}
 
   void HandleTranslationUnit(clang::ASTContext& context) override {
-    visitor_.Traverse(context);
+    visitor_.TraverseDecl(context.getTranslationUnitDecl());
   }
 
  private:
@@ -63,8 +63,6 @@
       options_.check_implicit_copy_ctors = true;
     } else if (args[i] == "no-realpath") {
       options_.no_realpath = true;
-    } else if (args[i] == "check-ipc") {
-      options_.check_ipc = true;
     } else {
       parsed = false;
       llvm::errs() << "Unknown clang plugin argument: " << args[i] << "\n";