Flow analysis: fix "why not promoted" info for nullable_expression_call_error

Previously, I only did the proper flow analysis integration in the
case where `useNewMethodInvocationEncoding` was true, so these cases
didn't work when it was false.

Bug: #44898
Change-Id: I6e126f4b8dc9a159087669c3d6ffa332373f8ce4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/193590
Commit-Queue: Paul Berry <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: stereotype441

pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart

@@ -3445,13 +3445,13 @@ class TypeInferrerImpl implements TypeInferrer {
           kind, originalReceiver, originalName,
           resultType: calleeType, interfaceTarget: originalTarget)
         ..fileOffset = fileOffset;
-      flowAnalysis.propertyGet(
-          originalPropertyGet, originalReceiver, originalName.text, calleeType);
     } else {
       originalPropertyGet =
           new PropertyGet(originalReceiver, originalName, originalTarget)
             ..fileOffset = fileOffset;
     }
+    flowAnalysis.propertyGet(
+        originalPropertyGet, originalReceiver, originalName.text, calleeType);
     Expression propertyGet = originalPropertyGet;
     if (receiver is! ThisExpression &&
         calleeType is! DynamicType &&