Make ASTHelpers.getSymbol(Tree) delegate to the `MemberReferenceTre…

…e` overload.

This may or may not actually change behavior: The handling that I added in e5a6d0d was definitely important for `MethodInvocationTree`, since it affects behavior when code uses static imports. However, static imports can't be used with a `MemberReferenceTree`, so the change might not be important there. Still, as I noted in that previous CL's description, I get the impression that this might also help with cases like `someSerializable.equals`—and presumably `someSerializable::equals`, too.

Anyway, this change seems clearly like either an improvement in behavior or a no-op that makes the implementation more consistent, so either way feels like a win.

PiperOrigin-RevId: 656731744

check_api/src/main/java/com/google/errorprone/util/ASTHelpers.java

@@ -260,14 +260,13 @@ public static boolean sameVariable(ExpressionTree expr1, ExpressionTree expr2) {
       return ((JCIdent) tree).sym;
     }
     if (tree instanceof JCMethodInvocation) {
-      return ASTHelpers.getSymbol((MethodInvocationTree) tree);
+      return getSymbol((MethodInvocationTree) tree);
     }
     if (tree instanceof JCNewClass) {
-      return ASTHelpers.getSymbol((NewClassTree) tree);
+      return getSymbol((NewClassTree) tree);
     }
     if (tree instanceof MemberReferenceTree) {
-      // TODO: b/285157761 - Delegate to the MemberReferenceTree overload.
-      return ((JCMemberReference) tree).sym;
+      return getSymbol((MemberReferenceTree) tree);
     }
     if (tree instanceof JCAnnotatedType) {
       return getSymbol(((JCAnnotatedType) tree).underlyingType);