[web] Fix 2 bugs in emdawnwebgpu (patches dawn) (#27641)
### Description
Fix 2 bugs in emdawnwebgpu.
1. Fix incorrect handling for device lost. See also:
- issue: [Unexpected exit on device lost handler [492350387] -
Chromium](https://issues.chromium.org/issues/492350387)
- PR: [emdawnwebgpu: Add runtimeKeepalive for device.lost handler by
fs-eire · Pull Request #57 ·
google/d…](https://github.com/google/dawn/pull/57)
(but dawn does not accept PR with copilot as co-author, so just for
reference)
2. Fix wrong call to WGPUBufferImpl constructor. See also:
- issue: [Incorrect WGPUBufferImpl constructor called from
importJsBuffer](https://issues.chromium.org/issues/492539247)
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