Split bindings/v8/custom into core and modules.

Source/bindings/bindings.gni

Index: Source/bindings/bindings.gni
diff --git a/Source/bindings/bindings.gni b/Source/bindings/bindings.gni
index 73b987df4f3218c539d354d6ac5b61bac8f07d33..f3862660c2d48cb952e4863f12502dfbf278aeda 100644
--- a/Source/bindings/bindings.gni
+++ b/Source/bindings/bindings.gni
@@ -20,6 +20,21 @@ bindings_v8_custom_files = get_path_info(
                 bindings_v8_custom_dir),
     "abspath")
 
+# modules/v8/custom/custom.gypi ------------------------------------------------
+
+# These paths are relative to v8/custom.
+_v8_modules_custom_gypi = exec_script(
+    "//build/gypi_to_gn.py",
+    [ rebase_path("v8/custom/custom.gypi") ],
+    "scope",
+    [ "v8/custom/custom.gypi" ])
+
+bindings_v8_modules_custom_dir = get_path_info("v8/custom", "abspath")
+bindings_v8_modules_custom_files = get_path_info(
+    rebase_path(_v8_custom_gypi.bindings_v8_modules_custom_files, ".",
+                bindings_v8_modules_custom_dir),
+    "abspath")
+
 # v8/v8.gypi -------------------------------------------------------------------
 
 # These paths are relative to v8.
@@ -34,7 +49,7 @@ bindings_v8_dir = get_path_info("v8", "abspath")
 # v8.gypi references includes a reference to the custom_files list. Manually
 # expand that.
 _rel_bindings_v8_files = _v8_gypi.bindings_v8_files
-_rel_bindings_v8_files -= [ "<@(bindings_v8_custom_files)" ]
+_rel_bindings_v8_files -= [ "<@(bindings_v8_custom_files)", "<@(bindings_v8_modules_custom_files)" ]
 bindings_v8_files = get_path_info(
     rebase_path(_rel_bindings_v8_files, ".", "v8"),
     "abspath")