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

Source/core/BUILD.gn

Index: Source/core/BUILD.gn
diff --git a/Source/core/BUILD.gn b/Source/core/BUILD.gn
index 68f13db1dc99d2471b95d27d8634e86950f30bd8..d9d51190ee09c3f7b8818c2570e23a04c1d98312 100644
--- a/Source/core/BUILD.gn
+++ b/Source/core/BUILD.gn
@@ -298,10 +298,13 @@ source_set("testing") {
 
   deps = [
     ":core",
+    ":core_generated",
   ]
 
   sources = webcore_testing_files
   sources += [
+    "$bindings_core_v8_output_dir/V8DictionaryTest.cpp",
+    "$bindings_core_v8_output_dir/V8DictionaryTest.h",
     "$bindings_core_v8_output_dir/V8GarbageCollectedScriptWrappable.cpp",
     "$bindings_core_v8_output_dir/V8GarbageCollectedScriptWrappable.h",
     "$bindings_core_v8_output_dir/V8GCObservation.cpp",
@@ -328,6 +331,8 @@ source_set("testing") {
     "$bindings_core_v8_output_dir/V8LayerRectList.h",
     "$bindings_core_v8_output_dir/V8RefCountedScriptWrappable.cpp",
     "$bindings_core_v8_output_dir/V8RefCountedScriptWrappable.h",
+    "$bindings_core_v8_output_dir/V8TestingDictionary.cpp",
+    "$bindings_core_v8_output_dir/V8TestingDictionary.h",
   ]
 }