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

pkg/analysis_server/test/services/correction/assist_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library test.services.correction.assist;
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/correction/assist.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:unittest/unittest.dart';
@@ skipping 595 matching lines @@
   void test_assignToLocalVariable_alreadyAssignment() {
     resolveTestUnit('''
 main() {
   var vvv;
   vvv = 42;
 }
 ''');
     assertNoAssistAt('vvv =', AssistKind.ASSIGN_TO_LOCAL_VARIABLE);
   }
 
+  void test_assignToLocalVariable_invocationArgument() {
+    resolveTestUnit(r'''
+main() {
+  f(12345);
+}
+int f(p) {}
+''');
+    assertNoAssistAt('345', AssistKind.ASSIGN_TO_LOCAL_VARIABLE);
+  }
+
   void test_assignToLocalVariable_throw() {
     resolveTestUnit('''
 main() {
   throw 42;
 }
 ''');
     assertNoAssistAt('throw ', AssistKind.ASSIGN_TO_LOCAL_VARIABLE);
   }
 
   void test_assignToLocalVariable_void() {
@@ skipping 2021 matching lines @@
       positions.add(new Position(testFile, offset));
     }
     return positions;
   }
 
   void _setStartEndSelection() {
     offset = findOffset('// start\n') + '// start\n'.length;
     length = findOffset('// end') - offset;
   }
 }