Revert "Updates return type for bitmask fields to be the Flag version."

This reverts commit 195cb637732ebe84ba08d09ba8834fa532912dc4.

Reason for revert: Suspected to be breaking the roll into Chromium.
(`error: undefined symbol: enum WGPUBufferUsage __cdecl dawn::native::NativeBufferGetUsage(struct WGPUBufferImpl *)`)


Original change's description:
> Updates return type for bitmask fields to be the Flag version.
>
> github.com/webgpu-native/webgpu-headers/issues/172
>
> Change-Id: Id1ec887cbd1cc3fefdce2f20bde89b3e529a96fa
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/134541
> Kokoro: Kokoro <noreply+kokoro@google.com>
> Reviewed-by: Kai Ninomiya <kainino@chromium.org>
> Commit-Queue: Loko Kung <lokokung@google.com>
> Reviewed-by: Austin Eng <enga@chromium.org>

TBR=kainino@chromium.org,enga@chromium.org,noreply+kokoro@google.com,dawn-scoped@luci-project-accounts.iam.gserviceaccount.com,lokokung@google.com

Change-Id: I3f06af96ad62df755453913804fc52a42eb8290d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/135180
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
diff --git a/generator/dawn_json_generator.py b/generator/dawn_json_generator.py
index 2b3bc5f..a6fccc4 100644
--- a/generator/dawn_json_generator.py
+++ b/generator/dawn_json_generator.py
@@ -705,13 +705,6 @@
         return c_prefix + name.CamelCase()
 
 
-def as_cReturnType(c_prefix, typ):
-    if typ.category != 'bitmask':
-        return as_cType(c_prefix, typ.name)
-    else:
-        return as_cType(c_prefix, typ.name) + 'Flags'
-
-
 def as_cppType(name):
     if name.native:
         return name.concatcase()
@@ -883,7 +876,6 @@
             'as_MethodSuffix': as_MethodSuffix,
             'as_cProc': as_cProc,
             'as_cType': lambda name: as_cType(c_prefix, name),
-            'as_cReturnType': lambda typ: as_cReturnType(c_prefix, typ),
             'as_cppType': as_cppType,
             'as_jsEnumValue': as_jsEnumValue,
             'convert_cType_to_cppType': convert_cType_to_cppType,
diff --git a/generator/templates/api.h b/generator/templates/api.h
index 4413931..baf0cc6 100644
--- a/generator/templates/api.h
+++ b/generator/templates/api.h
@@ -167,7 +167,7 @@
 {% for type in by_category["object"] if len(c_methods(type)) > 0 %}
     // Procs of {{type.name.CamelCase()}}
     {% for method in c_methods(type) %}
-        typedef {{as_cReturnType(method.return_type)}} (*{{as_cProc(type.name, method.name)}})(
+        typedef {{as_cType(method.return_type.name)}} (*{{as_cProc(type.name, method.name)}})(
             {{-as_cType(type.name)}} {{as_varName(type.name)}}
             {%- for arg in method.arguments -%}
                 ,{{" "}}
diff --git a/generator/templates/dawn/native/ProcTable.cpp b/generator/templates/dawn/native/ProcTable.cpp
index ae4e627..7b1922b 100644
--- a/generator/templates/dawn/native/ProcTable.cpp
+++ b/generator/templates/dawn/native/ProcTable.cpp
@@ -36,7 +36,7 @@
         {% for method in c_methods(type) %}
             {% set suffix = as_MethodSuffix(type.name, method.name) %}
 
-            {{as_cReturnType(method.return_type)}} Native{{suffix}}(
+            {{as_cType(method.return_type.name)}} Native{{suffix}}(
                 {{-as_cType(type.name)}} cSelf
                 {%- for arg in method.arguments -%}
                     , {{as_annotated_cType(arg)}}
diff --git a/generator/templates/dawn/wire/client/ApiProcs.cpp b/generator/templates/dawn/wire/client/ApiProcs.cpp
index 9c8656d..85fe15d 100644
--- a/generator/templates/dawn/wire/client/ApiProcs.cpp
+++ b/generator/templates/dawn/wire/client/ApiProcs.cpp
@@ -42,7 +42,7 @@
             {% if Suffix in client_handwritten_commands %}
                 static
             {% endif %}
-            {{as_cReturnType(method.return_type)}} Client{{Suffix}}(
+            {{as_cType(method.return_type.name)}} Client{{Suffix}}(
                 {{-cType}} cSelf
                 {%- for arg in method.arguments -%}
                     , {{as_annotated_cType(arg)}}
diff --git a/generator/templates/dawn_thread_dispatch_proc.cpp b/generator/templates/dawn_thread_dispatch_proc.cpp
index bff025d..fc79464 100644
--- a/generator/templates/dawn_thread_dispatch_proc.cpp
+++ b/generator/templates/dawn_thread_dispatch_proc.cpp
@@ -32,7 +32,7 @@
 
 {% for type in by_category["object"] %}
     {% for method in c_methods(type) %}
-        static {{as_cReturnType(method.return_type)}} ThreadDispatch{{as_MethodSuffix(type.name, method.name)}}(
+        static {{as_cType(method.return_type.name)}} ThreadDispatch{{as_MethodSuffix(type.name, method.name)}}(
             {{-as_cType(type.name)}} {{as_varName(type.name)}}
             {%- for arg in method.arguments -%}
                 , {{as_annotated_cType(arg)}}