[parsing] Fix maybe-assigned for loop variables.

src/parsing/pattern-rewriter.cc

Index: src/parsing/pattern-rewriter.cc
diff --git a/src/parsing/pattern-rewriter.cc b/src/parsing/pattern-rewriter.cc
index e22a67b9762ae165fcea959c91bfe0bd8e7e475c..2dad31d8d3a0d1723c392ae3083c746db62ca6ba 100644
--- a/src/parsing/pattern-rewriter.cc
+++ b/src/parsing/pattern-rewriter.cc
@@ -177,6 +177,8 @@ void Parser::PatternRewriter::VisitVariableProxy(VariableProxy* pattern) {
   // If there's no initializer, we're done.
   if (value == nullptr) return;
 
+  MarkLoopVariableAsAssigned(var_init_scope, proxy->var());
+
   // A declaration of the form:
   //
   //    var v = x;