msvs: Revert r1920 and add a test for excluded idl

pylib/gyp/generator/msvs.py

Index: pylib/gyp/generator/msvs.py
diff --git a/pylib/gyp/generator/msvs.py b/pylib/gyp/generator/msvs.py
index e786c0b8c96fa96982e8f40106b3961200b96366..843f97fcd829122751ccb5c3d908bf3309d28c2a 100644
--- a/pylib/gyp/generator/msvs.py
+++ b/pylib/gyp/generator/msvs.py
@@ -833,7 +833,7 @@ def _AdjustSourcesForRules(spec, rules, sources, excluded_sources):
         outputs = OrderedSet(_FixPaths(outputs))
         inputs.remove(_FixPath(trigger_file))
         sources.update(inputs)
-        if spec['type'] != 'none' and not spec.get('msvs_external_builder'):
+        if not spec.get('msvs_external_builder'):
           excluded_sources.update(inputs)
         sources.update(outputs)
 
@@ -1392,7 +1392,7 @@ def _PrepareListOfSources(spec, generator_flags, gyp_file):
     # Add all inputs to sources and excluded sources.
     inputs = OrderedSet(inputs)
     sources.update(inputs)
-    if spec['type'] != 'none' and not spec.get('msvs_external_builder'):
+    if not spec.get('msvs_external_builder'):
       excluded_sources.update(inputs)
     if int(a.get('process_outputs_as_sources', False)):
       _AddNormalizedSources(sources, a.get('outputs', []))