Implement '[SecureContext]' IDL attribute for partial interfaces.

third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py

Index: third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
diff --git a/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py b/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
index c728e722013428e02cfc9e9cb342c256b65bb85c..5a032ed2d27402592a7c288064bdc467c15983d6 100644
--- a/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
+++ b/third_party/WebKit/Source/bindings/scripts/interface_dependency_resolver.py
@@ -47,6 +47,7 @@ from utilities import idl_filename_to_component, is_valid_component_dependency,
 DEPENDENCY_EXTENDED_ATTRIBUTES = frozenset([
     'OriginTrialEnabled',
     'RuntimeEnabled',
+    'SecureContext',
 ])
 
 
@@ -263,11 +264,10 @@ def transfer_extended_attributes(dependency_interface, dependency_interface_base
     """
     merged_extended_attributes = {}
     for key in DEPENDENCY_EXTENDED_ATTRIBUTES:
-        value = dependency_interface.extended_attributes.get(key)
-        if not value:
+        if key not in dependency_interface.extended_attributes:
             continue
 
-        merged_extended_attributes[key] = value
+        merged_extended_attributes[key] = dependency_interface.extended_attributes[key]
         # Remove the merged attributes from the original dependency interface.
         # This ensures that if other dependency interfaces are merged onto this
         # one, its extended_attributes do not leak through