[webgpu] Fix memory leak in buffer manager (#2525)
[webgpu] Fix memory leak in buffer manager (#2525)

BUG

* [webgpu] Fix memory leak in buffer manager

* [webgpu] Fix memory leak in buffer manager

* Fix typo

Co-authored-by: Ann Yuan <0ba812ddf6511e18d741d84e2d0ef22781e9b55d@google.com>

tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs,tensorflow/tfjs