IDL: Add build target for IDL dictionary impl generation in core

Source/bindings/core/idl.gni

Index: Source/bindings/core/idl.gni
diff --git a/Source/bindings/core/idl.gni b/Source/bindings/core/idl.gni
index 39cb5fff5ad545702e9dff2a73811abd5ff19eca..701445e8f2485ba6adcf323ec3f4fb69243efb24 100644
--- a/Source/bindings/core/idl.gni
+++ b/Source/bindings/core/idl.gni
@@ -8,17 +8,21 @@ import("//third_party/WebKit/Source/core/core.gni")
 # Don't actually read idl.gypi since that just defines variables in terms of
 # others, which gypi_to_gn doesn't handle.
 
+core_testing_definition_idl_files =
+  core_testing_dictionary_idl_files +
+  webcore_testing_idl_files
+
 # IDL file lists; see: http://www.chromium.org/developers/web-idl-interfaces
 # Interface IDL files: generate individual bindings (includes testing)
 core_interface_idl_files =
   core_idl_files +
-  webcore_testing_idl_files +
+  core_testing_definition_idl_files +
   generated_webcore_testing_idl_files
 
 # Static IDL files
 core_static_interface_idl_files =
   core_idl_files +
-  webcore_testing_idl_files
+  core_testing_definition_idl_files
 core_static_dependency_idl_files =
   core_dependency_idl_files