blink_gc_plugin: retire overloaded traceImpl detection and handling.

tools/clang/blink_gc_plugin/tests/traceimpl_error.cpp

Index: tools/clang/blink_gc_plugin/tests/traceimpl_error.cpp
diff --git a/tools/clang/blink_gc_plugin/tests/traceimpl_error.cpp b/tools/clang/blink_gc_plugin/tests/traceimpl_error.cpp
index c14e52d6dfcc1fee290e0f8bf609b7fd287fc1ea..0c49939f6f90c1cc98cd2768010a6efdc8b48ab7 100644
--- a/tools/clang/blink_gc_plugin/tests/traceimpl_error.cpp
+++ b/tools/clang/blink_gc_plugin/tests/traceimpl_error.cpp
@@ -7,22 +7,10 @@
 namespace blink {
 
 void TraceImplExternWithUntracedMember::Trace(Visitor* visitor) {
-  TraceImpl(visitor);
-}
-
-template <typename VisitorDispatcher>
-inline void TraceImplExternWithUntracedMember::TraceImpl(
-    VisitorDispatcher visitor) {
   // Should get a warning as well.
 }
 
 void TraceImplExternWithUntracedBase::Trace(Visitor* visitor) {
-  TraceImpl(visitor);
-}
-
-template <typename VisitorDispatcher>
-inline void TraceImplExternWithUntracedBase::TraceImpl(
-    VisitorDispatcher visitor) {
   // Ditto.
 }