[WebGPU] Replaced "long" with "unsigned long" for stencilLoadValue

https://gpuweb.github.io/gpuweb/#depth-stencil-attachments says
stencilLoadValue is "unsigned long", not "long". This CL fixes it.

Bug: 877147
Change-Id: I73592bc24800ee15c1b105473f6e79a52e8abe57
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1815019Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#699339}

third_party/blink/renderer/bindings/modules/v8/generated.gni

@@ -52,8 +52,8 @@ bindings_modules_generated_union_type_files = [
   "$bindings_modules_v8_output_dir/gpu_load_op_or_gpu_color.h",
   "$bindings_modules_v8_output_dir/gpu_load_op_or_float.cc",
   "$bindings_modules_v8_output_dir/gpu_load_op_or_float.h",
-  "$bindings_modules_v8_output_dir/gpu_load_op_or_long.cc",
-  "$bindings_modules_v8_output_dir/gpu_load_op_or_long.h",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_unsigned_long.cc",
+  "$bindings_modules_v8_output_dir/gpu_load_op_or_unsigned_long.h",
   "$bindings_modules_v8_output_dir/gpu_sampler_or_gpu_texture_view_or_gpu_buffer_binding.cc",
   "$bindings_modules_v8_output_dir/gpu_sampler_or_gpu_texture_view_or_gpu_buffer_binding.h",
   "$bindings_modules_v8_output_dir/html_canvas_element_or_offscreen_canvas.cc",

third_party/blink/renderer/modules/webgpu/gpu_command_encoder.cc

@@ -82,9 +82,10 @@ DawnRenderPassDepthStencilAttachmentDescriptor AsDawnType(
     dawn_desc.stencilLoadOp = AsDawnEnum<DawnLoadOp>(gpuLoadOp);
     dawn_desc.clearStencil = 0;
 
-  } else if (webgpu_desc->stencilLoadValue().IsLong()) {
+  } else if (webgpu_desc->stencilLoadValue().IsUnsignedLong()) {
     dawn_desc.stencilLoadOp = DAWN_LOAD_OP_CLEAR;
-    dawn_desc.clearStencil = webgpu_desc->stencilLoadValue().GetAsLong();
+    dawn_desc.clearStencil =
+        webgpu_desc->stencilLoadValue().GetAsUnsignedLong();
 
   } else {
     NOTREACHED();

third_party/blink/renderer/modules/webgpu/gpu_render_pass_depth_stencil_attachment_descriptor.idl

@@ -10,6 +10,6 @@ dictionary GPURenderPassDepthStencilAttachmentDescriptor {
     required (GPULoadOp or float) depthLoadValue;
     required GPUStoreOp depthStoreOp;
 
-    required (GPULoadOp or long) stencilLoadValue;
+    required (GPULoadOp or unsigned long) stencilLoadValue;
     required GPUStoreOp stencilStoreOp;
 };