Issue 25827. Don't propose to remove the type of an incomplete variable declaration.

R=brianwilkerson@google.com
BUG= #25827

Review URL: https://codereview.chromium.org/1753893002 .

Author: scheglov

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

@@ -1444,6 +1444,12 @@ class AssistProcessor {
       _coverageMarker();
       return;
     }
+    // ignore if an incomplete variable declaration
+    if (declarationList.variables.length == 1 &&
+        declarationList.variables[0].name.isSynthetic) {
+      _coverageMarker();
+      return;
+    }
     // must be not after the name of the variable
     VariableDeclaration firstVariable = declarationList.variables[0];
     if (selectionOffset > firstVariable.name.end) {

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

@@ -3317,6 +3317,14 @@ main() {
 ''');
   }
 
+  test_removeTypeAnnotation_topLevelVariable_BAD_syntheticName() async {
+    verifyNoTestUnitErrors = false;
+    resolveTestUnit('''
+MyType
+''');
+    await assertNoAssistAt('MyType', DartAssistKind.REMOVE_TYPE_ANNOTATION);
+  }
+
   test_removeTypeAnnotation_topLevelVariable_OK() async {
     resolveTestUnit('''
 int V = 1;