webnn: Migrate slice validation tests to WPTs
This CL adds WPT tests for slice and removes the unit tests
MLGraphBuilderTest.SliceTest, MLGraphTestMojo.SliceTest and
MLGraphTest.SliceTest.
Bug: 327337526, 328026885
Change-Id: I1774d86972d6ab0a02080d9f36d1ce939bea69f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5481673
Commit-Queue: Shanxing Mei shanxing.mei@intel.com
Reviewed-by: ningxin hu ningxin.hu@intel.com
Reviewed-by: Austin Sullivan asully@chromium.org
Cr-Commit-Position: refs/heads/main@{#1292942}