Generate web, devtools files into their own sub-dirs.

Source/modules/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//third_party/WebKit/Source/bindings/bindings.gni")
 import("//third_party/WebKit/Source/bindings/modules/v8/generated.gni")
 import("//third_party/WebKit/Source/build/make_file_arrays.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
 import("//third_party/WebKit/Source/modules/modules.gni")
 
@@ skipping 35 matching lines @@
   if (is_win) {
     cflags = [
       "/wd4267",  # Size to int truncations.
       "/wd4334",  # Result of 32-bit shift implicitly converted to 64 bits.
     ]
   }
 }
 
 # GYP version: WebKit/Source/modules/modules.gyp:modules (FetchPolyfill action)
 make_file_arrays("modules_fetch_polyfill") {
-  filename = "FetchPolyfill"
+  filename = "modules/FetchPolyfill"
   resources = [
     "serviceworkers/polyfills/fetchPolyfill.js",
   ]
   namespace = "WebCore"
 }
 
 # GYP version: WebKit/Source/modules/modules.gyp:modules (CachePolyfill action)
 make_file_arrays("modules_cache_polyfill") {
-  filename = "CachePolyfill"
+  filename = "modules/CachePolyfill"
   resources = [
     "serviceworkers/polyfills/cachePolyfill.js",
   ]
   namespace = "WebCore"
 }
 
 # GYP version: WebKit/Source/modules/modules.gyp:modules (CacheStoragePolyfill action)
 make_file_arrays("modules_cache_storage_polyfill") {
-  filename = "CacheStoragePolyfill"
+  filename = "modules/CacheStoragePolyfill"
   resources = [
     "serviceworkers/polyfills/cacheStoragePolyfill.js",
   ]
   namespace = "WebCore"
 }
 
 # GYP version: WebKit/Source/modules/modules.gyp:modules_testing
 source_set("modules_testing") {
   sources = modules_testing_files
 
   configs += [
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     "//third_party/WebKit/Source/core",
   ]
 }
 
 # GYP version: WebKit/Source/modules/modules.gyp:make_modules_generated
 group("make_modules_generated") {
   deps = [
     "//third_party/WebKit/Source/core:core_event_interfaces",
     "//third_party/WebKit/Source/bindings/modules:bindings_modules_generated",
   ]
 }