Revert "Allowing `e` of any type in `void f(...) => e` in the analyzer."

pkg/analyzer/lib/src/generated/error_verifier.dart

Index: pkg/analyzer/lib/src/generated/error_verifier.dart
diff --git a/pkg/analyzer/lib/src/generated/error_verifier.dart b/pkg/analyzer/lib/src/generated/error_verifier.dart
index f8a9177bf6be18b66157a50c187d595de2ea631a..ce1dfe702f438e83d9493bd27671865965180383 100644
--- a/pkg/analyzer/lib/src/generated/error_verifier.dart
+++ b/pkg/analyzer/lib/src/generated/error_verifier.dart
@@ -660,8 +660,7 @@ class ErrorVerifier extends RecursiveAstVisitor<Object> {
           function is PropertyAccessorElement &&
           function.isSetter;
       if (!isSetterWithImplicitReturn) {
-        _checkForReturnOfInvalidType(node.expression, expectedReturnType,
-            isArrowFunction: true);
+        _checkForReturnOfInvalidType(node.expression, expectedReturnType);
       }
       return super.visitExpressionFunctionBody(node);
     } finally {
@@ -5599,8 +5598,7 @@ class ErrorVerifier extends RecursiveAstVisitor<Object> {
    * See [StaticTypeWarningCode.RETURN_OF_INVALID_TYPE].
    */
   void _checkForReturnOfInvalidType(
-      Expression returnExpression, DartType expectedReturnType,
-      {bool isArrowFunction = false}) {
+      Expression returnExpression, DartType expectedReturnType) {
     if (_enclosingFunction == null) {
       return;
     }
@@ -5612,10 +5610,6 @@ class ErrorVerifier extends RecursiveAstVisitor<Object> {
     }
     DartType staticReturnType = _computeReturnTypeForMethod(returnExpression);
     if (expectedReturnType.isVoid) {
-      if (isArrowFunction) {
-        // "void f(..) => e" admits all types for "e".
-        return;
-      }
       if (staticReturnType.isVoid ||
           staticReturnType.isDynamic ||
           staticReturnType.isBottom ||