[DevTools] Cleanup frontend-in-iframe support.

Source/devtools/BUILD.gn

Index: Source/devtools/BUILD.gn
diff --git a/Source/devtools/BUILD.gn b/Source/devtools/BUILD.gn
index 545dc718ddb82c33846930bc058ddf4958bde56d..5a96594a3070a2d0d5045be53d9c9fcace2f8386 100644
--- a/Source/devtools/BUILD.gn
+++ b/Source/devtools/BUILD.gn
@@ -78,7 +78,7 @@ visibility = [ "//third_party/WebKit/*" ]
 
 group("devtools_frontend_resources") {
   deps = [
-    ":copy_devtools_html",
+    ":copy_compatibility_scripts",
     ":copy_inspector_images",
     ":devtools_extension_api",
     ":frontend_protocol_sources",
@@ -96,8 +96,8 @@ group("devtools_frontend_resources") {
   }
 }
 
-copy("copy_devtools_html") {
-  sources = [ "front_end/devtools.html", "front_end/devtools.js" ]
+copy("copy_compatibility_scripts") {
+  sources = gypi_values.devtools_compatibility_scripts
   outputs = [ resources_out_dir + "{{source_file_part}}" ]
 }
 
@@ -111,17 +111,15 @@ action("generate_devtools_grd") {
 
   deps = [ ":devtools_frontend_resources" ]
   static_files_list = "$target_gen_dir/devtools_static_grd_files.tmp"
-  inputs = gypi_values.devtools_image_files + all_devtools_files + [
-    static_files_list
-  ]
+  inputs = gypi_values.devtools_image_files + all_devtools_files
+  inputs += gypi_values.devtools_compatibility_scripts
+  inputs += [ static_files_list ]
 
   static_files = []
 
   if (debug_devtools) {
     # Debug: all files are picked as-is.
     generated_files = generated_scripts + [
-      resources_out_dir + "devtools.html",
-      resources_out_dir + "devtools.js",
       resources_out_dir + "inspector.html",
       resources_out_dir + "toolbox.html",
     ]
@@ -130,8 +128,6 @@ action("generate_devtools_grd") {
     # Release: pick compiled non-remote files and lazy-loaded CSS.
     # TODO(dgozman): remove remote modules from here once experiment is over.
     generated_files = [
-      resources_out_dir + "devtools.html",
-      resources_out_dir + "devtools.js",
       resources_out_dir + "inspector.css",
       resources_out_dir + "inspector.html",
       resources_out_dir + "inspector.js",
@@ -177,7 +173,8 @@ action("generate_devtools_grd") {
   ]
 
   args = rebase_path(generated_files, root_build_dir) +
-    rebase_path(generated_files, root_build_dir) + [
+    rebase_path(generated_files, root_build_dir) +
+    rebase_path(gypi_values.devtools_compatibility_scripts, root_build_dir) + [
     "--static_files_list", rebase_path(static_files_list, root_build_dir),
     "--relative_path_dirs" ] +
     rebase_path(relative_path_dirs, root_build_dir) + [