Reduce `_DoubleClampVisitor` false positives (#128539)

I'm getting a few false positives in https://github.com/flutter/flutter/pull/128522/checks from the `num.clamp` checker since I introduced a class with a `clamp` method.

dev/bots/analyze.dart

@@ -239,7 +239,15 @@ class _DoubleClampVisitor extends RecursiveAstVisitor<CompilationUnit> {
 
   @override
   CompilationUnit? visitMethodInvocation(MethodInvocation node) {
-    if (node.methodName.name == 'clamp') {
+    final NodeList<Expression> arguments = node.argumentList.arguments;
+    // This may produce false positives when `node.target` is not a subtype of
+    // num. The static type of `node.target` isn't guaranteed to be resolved at
+    // this time. Check whether the argument list consists of 2 positional args
+    // to reduce false positives.
+    final bool isNumClampInvocation = node.methodName.name == 'clamp'
+                                   && arguments.length == 2
+                                   && !arguments.any((Expression exp) => exp is NamedExpression);
+    if (isNumClampInvocation) {
       final _Line line = _getLine(parseResult, node.function.offset);
       if (!line.content.contains('// ignore_clamp_double_lint')) {
         clamps.add(line);