Don't propose 'Assign to local variable' when in arguments list.

pkg/analysis_server/lib/src/services/correction/assist_internal.dart

Index: pkg/analysis_server/lib/src/services/correction/assist_internal.dart
diff --git a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
index bb6726d1c2ae4eaabd16a35b88afcb3b86ae5a4e..376e4140cb4b7b9f5a07e82f20be4ac399386065 100644
--- a/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
+++ b/pkg/analysis_server/lib/src/services/correction/assist_internal.dart
@@ -362,6 +362,11 @@ class AssistProcessor {
     // prepare expression
     Expression expression = expressionStatement.expression;
     int offset = expression.offset;
+    // ignore if in arguments
+    if (node.getAncestor((node) => node is ArgumentList) != null) {
+      _coverageMarker();
+      return;
+    }
     // ignore if already assignment
     if (expression is AssignmentExpression) {
       _coverageMarker();