[WebGPU] Remove 16bit normalized texture formats.

These were removed from WebGPU because they cannot be supported
everywhere, for example on recent Qualcomm chips.

BUG=dawn:128

Change-Id: I235539916730001ad329f9ad067da7599e109360
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1760959
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688708}

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

@@ -85,12 +85,6 @@ DawnTextureFormat AsDawnEnum<DawnTextureFormat>(
   }
 
   // Normal 16 bit formats
-  if (webgpu_enum == "r16unorm") {
-    return DAWN_TEXTURE_FORMAT_R16_UNORM;
-  }
-  if (webgpu_enum == "r16snorm") {
-    return DAWN_TEXTURE_FORMAT_R16_SNORM;
-  }
   if (webgpu_enum == "r16uint") {
     return DAWN_TEXTURE_FORMAT_R16_UINT;
   }
@@ -123,12 +117,6 @@ DawnTextureFormat AsDawnEnum<DawnTextureFormat>(
   if (webgpu_enum == "r32float") {
     return DAWN_TEXTURE_FORMAT_R32_FLOAT;
   }
-  if (webgpu_enum == "rg16unorm") {
-    return DAWN_TEXTURE_FORMAT_RG16_UNORM;
-  }
-  if (webgpu_enum == "rg16snorm") {
-    return DAWN_TEXTURE_FORMAT_RG16_SNORM;
-  }
   if (webgpu_enum == "rg16uint") {
     return DAWN_TEXTURE_FORMAT_RG16_UINT;
   }
@@ -178,12 +166,6 @@ DawnTextureFormat AsDawnEnum<DawnTextureFormat>(
   if (webgpu_enum == "rg32float") {
     return DAWN_TEXTURE_FORMAT_RG32_FLOAT;
   }
-  if (webgpu_enum == "rgba16unorm") {
-    return DAWN_TEXTURE_FORMAT_RGBA16_UNORM;
-  }
-  if (webgpu_enum == "rgba16snorm") {
-    return DAWN_TEXTURE_FORMAT_RGBA16_SNORM;
-  }
   if (webgpu_enum == "rgba16uint") {
     return DAWN_TEXTURE_FORMAT_RGBA16_UINT;
   }

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

@@ -27,8 +27,6 @@ enum GPUTextureFormat {
     "r8uint",
     "r8sint",
     /* Normal 16 bit formats */
-    "r16unorm",
-    "r16snorm",
     "r16uint",
     "r16sint",
     "r16float",
@@ -40,8 +38,6 @@ enum GPUTextureFormat {
     "r32uint",
     "r32sint",
     "r32float",
-    "rg16unorm",
-    "rg16snorm",
     "rg16uint",
     "rg16sint",
     "rg16float",
@@ -59,8 +55,6 @@ enum GPUTextureFormat {
     "rg32uint",
     "rg32sint",
     "rg32float",
-    "rgba16unorm",
-    "rgba16snorm",
     "rgba16uint",
     "rgba16sint",
     "rgba16float",