Re-apply workaround for bug fixed by closures containing type promotions in variables with inferred types.

ba5644b fixed an analyzer bug causing
a crash when a top level variable requiring type inference contained a
closure involving type promotion, and removed some explicit types that
were present in the analyzer to work around the bug.

Although the bug has been fixed now, the fix hasn't rolled out in a
release of the SDK.  So to avoid people seeing analysis server crashes
when editing the analyzer, I'm re-introducing the workaround.

Change-Id: I5e61345021cd33cb9ad1f017a7619815a38c6a1c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/95667
Reviewed-by: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Paul Berry <[email protected]>

Author: stereotype441

pkg/analyzer/test/util/ast_type_matchers.dart

@@ -111,14 +111,18 @@ const isFieldDeclaration = const TypeMatcher<FieldDeclaration>();
 
 const isFieldFormalParameter = const TypeMatcher<FieldFormalParameter>();
 
-final isForEachStatement = predicate(
+/// TODO(paulberry): remove the explicit type `Matcher` once an SDK has been
+/// released that includes ba5644b76cb811e8f01ffb375b87d20d6295749c.
+final Matcher isForEachStatement = predicate(
     (Object o) => o is ForStatement2 && o.forLoopParts is ForEachParts);
 
 const isFormalParameter = const TypeMatcher<FormalParameter>();
 
 const isFormalParameterList = const TypeMatcher<FormalParameterList>();
 
-final isForStatement =
+/// TODO(paulberry): remove the explicit type `Matcher` once an SDK has been
+/// released that includes ba5644b76cb811e8f01ffb375b87d20d6295749c.
+final Matcher isForStatement =
     predicate((Object o) => o is ForStatement2 && o.forLoopParts is ForParts);
 
 const isFunctionBody = const TypeMatcher<FunctionBody>();
@@ -181,7 +185,10 @@ const isListLiteral = const TypeMatcher<ListLiteral>();
 
 const isLiteral = const TypeMatcher<Literal>();
 
-final isMapLiteral = predicate((Object o) => o is SetOrMapLiteral && o.isMap);
+/// TODO(paulberry): remove the explicit type `Matcher` once an SDK has been
+/// released that includes ba5644b76cb811e8f01ffb375b87d20d6295749c.
+final Matcher isMapLiteral =
+    predicate((Object o) => o is SetOrMapLiteral && o.isMap);
 
 const isMapLiteralEntry = const TypeMatcher<MapLiteralEntry>();
 
@@ -236,7 +243,10 @@ const isReturnStatement = const TypeMatcher<ReturnStatement>();
 
 const isScriptTag = const TypeMatcher<ScriptTag>();
 
-final isSetLiteral = predicate((Object o) => o is SetOrMapLiteral && o.isSet);
+/// TODO(paulberry): remove the explicit type `Matcher` once an SDK has been
+/// released that includes ba5644b76cb811e8f01ffb375b87d20d6295749c.
+final Matcher isSetLiteral =
+    predicate((Object o) => o is SetOrMapLiteral && o.isSet);
 
 const isShowCombinator = const TypeMatcher<ShowCombinator>();