blink_gc_plugin: retire overloaded traceImpl detection and handling.

tools/clang/blink_gc_plugin/tests/traceimpl_error.h

Index: tools/clang/blink_gc_plugin/tests/traceimpl_error.h
diff --git a/tools/clang/blink_gc_plugin/tests/traceimpl_error.h b/tools/clang/blink_gc_plugin/tests/traceimpl_error.h
index c7254d44f15476ee27d85cfc5e5e4f14682f1d87..d05c99c09aae284e35e297e73d96e87ae1589976 100644
--- a/tools/clang/blink_gc_plugin/tests/traceimpl_error.h
+++ b/tools/clang/blink_gc_plugin/tests/traceimpl_error.h
@@ -17,10 +17,7 @@ class X : public GarbageCollected<X> {
 class TraceImplInlinedWithUntracedMember
     : public GarbageCollected<TraceImplInlinedWithUntracedMember> {
  public:
-  void Trace(Visitor* visitor) { TraceImpl(visitor); }
-
-  template <typename VisitorDispatcher>
-  void TraceImpl(VisitorDispatcher visitor) {
+  void Trace(Visitor* visitor) {
     // Empty; should get complaints from the plugin for untraced x_.
   }
 
@@ -33,9 +30,6 @@ class TraceImplExternWithUntracedMember
  public:
   void Trace(Visitor* visitor);
 
-  template <typename VisitorDispatcher>
-  inline void TraceImpl(VisitorDispatcher);
-
  private:
   Member<X> x_;
 };
@@ -47,10 +41,7 @@ class Base : public GarbageCollected<Base> {
 
 class TraceImplInlineWithUntracedBase : public Base {
  public:
-  void Trace(Visitor* visitor) override { TraceImpl(visitor); }
-
-  template <typename VisitorDispatcher>
-  void TraceImpl(VisitorDispatcher visitor) {
+  void Trace(Visitor* visitor) override {
     // Empty; should get complaints from the plugin for untraced Base.
   }
 };
@@ -58,9 +49,6 @@ class TraceImplInlineWithUntracedBase : public Base {
 class TraceImplExternWithUntracedBase : public Base {
  public:
   void Trace(Visitor*) override;
-
-  template <typename VisitorDispatcher>
-  void TraceImpl(VisitorDispatcher visitor);
 };
 
 }