Merge pull request #33732 from DougGregor/forward-scan-unresolved-member-5.3

[5.3] [Constraint application] Find trailing closure direction more carefully.

Author: DougGregor

lib/Sema/CSApply.cpp

@@ -5703,7 +5703,7 @@ Expr *ExprRewriter::coerceCallArguments(
     SmallVector<LocatorPathElt, 4> path;
     auto anchor = locator.getLocatorParts(path);
     if (!path.empty() && path.back().is<LocatorPathElt::ApplyArgument>() &&
-        (isa<CallExpr>(anchor) || isa<SubscriptExpr>(anchor))) {
+        !isa<UnresolvedDotExpr>(anchor)) {
       auto locatorPtr = cs.getConstraintLocator(locator);
       assert(solution.trailingClosureMatchingChoices.count(locatorPtr) == 1);
       trailingClosureMatching = solution.trailingClosureMatchingChoices.find(