Reorganize Blink IDL build, delete obsolete GYP files.

third_party/WebKit/Source/bindings/core/idl.gni

-# 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/core/core.gni")
-import("//third_party/WebKit/Source/bindings/idl.gni")
-import("//third_party/WebKit/Source/core/core_idl_files.gni")
-
-# Don't actually read idl.gypi since that just defines variables in terms of
-# others, which gypi_to_gn doesn't handle.
-
-core_definition_idl_files = core_dictionary_idl_files + core_idl_files +
-                            core_idl_with_modules_dependency_files
-
-core_testing_definition_idl_files =
-    core_testing_dictionary_idl_files + webcore_testing_idl_files +
-    webcore_testing_idl_with_modules_dependency_files
-
-# Static IDL files
-core_static_interface_idl_files =
-    core_definition_idl_files + core_testing_definition_idl_files +
-    core_typedefs_enums_only_idl_files
-
-core_static_dependency_idl_files =
-    core_dependency_idl_files + webcore_testing_dependency_idl_files
-
-# Generated IDL files
-core_generated_interface_idl_files = generated_webcore_testing_idl_files  # interfaces
-core_generated_dependency_idl_files =
-    core_global_constructors_generated_idl_files  # partial interfaces
-
-# Dependency IDL files: don't generate individual bindings, but do process
-# in IDL dependency computation, and count as build dependencies
-# 'core_dependency_idl_files' is already used in Source/core, so avoid
-# collision
-core_all_dependency_idl_files =
-    core_static_dependency_idl_files + core_generated_dependency_idl_files