reset importmap with empty hasmap

Co-authored-by: Karl Seguin <[email protected]>

Author: krichprollsch

src/browser/ScriptManager.zig

@@ -124,7 +124,7 @@ pub fn reset(self: *ScriptManager) void {
     self.sync_modules.clearRetainingCapacity();
     // Our allocator is the page arena, it's been reset. We cannot use
     // clearAndRetainCapacity, since that space is no longer ours
-    self.importmap.clearAndFree(self.page.arena);
+    self.importmap = .empty
 
     self.clearList(&self.asyncs);
     self.clearList(&self.scripts);