Make EventInterfaces.in build step not depend on bindings generation

Source/bindings/bindings.gypi

 {
     'variables': {
-        'bindings_dir': ['.'],
+        'bindings_dir': '.',
+        'bindings_output_dir': '<(SHARED_INTERMEDIATE_DIR)/blink/bindings',
         'bindings_files': [
             'v8/ActiveDOMCallback.cpp',
             'v8/ActiveDOMCallback.h',
             'v8/ArrayValue.cpp',
             'v8/ArrayValue.h',
             'v8/BindingSecurity.cpp',
             'v8/BindingSecurity.h',
             'v8/CallbackPromiseAdapter.h',
             'v8/CustomElementBinding.cpp',
             'v8/CustomElementBinding.h',
@@ skipping 253 matching lines @@
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings12.cpp',
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings13.cpp',
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings14.cpp',
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings15.cpp',
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings16.cpp',
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings17.cpp',
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings18.cpp',
                     '<(SHARED_INTERMEDIATE_DIR)/blink/bindings/V8GeneratedBindings19.cpp',
                 ],
             }],
+
+          # The bindings generator can skip writing generated files if they are
+          # identical to the already existing file, which avoids recompilation.
+          # However, a dependency (earlier build step) having a newer timestamp
+          # than an output (later build step) confuses some build systems, so
+          # only use this on ninja, which explicitly supports this use case
+          # (gyp turns all actions into ninja restat rules).
+          ['"<(GENERATOR)"=="ninja"', {
+            'write_file_only_if_changed': '--write-file-only-if-changed 1',

[Nils Barth (inactive), 2014/03/27 06:43:51]

Needed by core.gyp, so move into .gypi, which is where it belongs anyway.

+          }, {
+            'write_file_only_if_changed': '--write-file-only-if-changed 0',
+          }],
         ],
     },
 }