Implement true LRU ordering, fix nested locks, and update async usage

Co-authored-by: shtankopro <shtankopro@gmail.com>

Author: cursoragent

.dart-sdk/dart-sdk/LICENSE

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+Copyright 2012, the Dart project authors.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google LLC nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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.dart-sdk/dart-sdk/README

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+The Dart SDK is a set of tools and libraries for the Dart programming language.
+
+You can find information about Dart online at https://dart.dev/.
+
+Here's a brief guide to what's in here:
+
+bin/               Binaries/scripts to compile, run, and manage Dart apps.
+  dart             Command line Dart tool
+  dartaotruntime   Minimal Dart runtime for running AOT modules
+  resources/       Resource files for dartdoc and devtools
+  snapshots/       AppAOT and AppJIT snapshots of various tools
+  utils/           Tools used by Dart compilers
+
+include/           header files that define the Dart embedding API for use by
+                   - C/C++ applications that embed the Dart Virtual machine
+                   - native libraries loaded into a dart application using FFI
+                     (https://dart.dev/guides/libraries/c-interop)
+
+lib/               Libraries that are shipped with the Dart runtime. More
+                   information is available at https://api.dart.dev.
+
+LICENSE            Description of Dart SDK license
+
+README             This file
+
+revision           The git commit ID of the SDK build
+                   (for example, 020b3efd3f0023c5db2097787f7cf778db837a8f).
+
+version            The version number of the SDK (for example, 2.12.1).