Auto merge of #11225 - izgzhen:patch-input-element-file, r=Manishearth

Implement file related functionalities in htmlinputelement and related

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy --faster` does not report any errors
- [x] These changes is related to #11131
- [x] These changes do not require tests because it is a partial implementation

1. Improve the `filemanager_thread` by adding type string and create `SelectedFile`
2. Fill several gaps in `htmlinputelement` implementation related to file type
3. Improve the `File` interface to accommodate the above changes
4. Integrate changes introduced by PR #11189

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components/script/dom/bindings/trace.rs

@@ -60,7 +60,7 @@ use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheThread};
 use net_traits::response::HttpsState;
 use net_traits::storage_thread::StorageType;
-use net_traits::{Metadata, NetworkError};
+use net_traits::{Metadata, NetworkError, ResourceThreads};
 use offscreen_gl_context::GLLimits;
 use profile_traits::mem::ProfilerChan as MemProfilerChan;
 use profile_traits::time::ProfilerChan as TimeProfilerChan;
@@ -321,6 +321,7 @@ no_jsmanaged_fields!(HttpsState);
 no_jsmanaged_fields!(SharedRt);
 no_jsmanaged_fields!(TouchpadPressurePhase);
 no_jsmanaged_fields!(ReferrerPolicy);
+no_jsmanaged_fields!(ResourceThreads);
 
 impl JSTraceable for Box<ScriptChan + Send> {
     #[inline]