bindings: Do not refer partial interfaces' constructors

Partial interfaces do not have constructors, so we can't nominate
them as members of V8ContextSnapshotExternalReferences.


Bug: 806163
Change-Id: I28e20fac326d57851f6443cca7c0c53bc86680fb
Reviewed-on: https://chromium-review.googlesource.com/888181Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532081}

third_party/WebKit/Source/bindings/scripts/generate_v8_context_snapshot_external_references.py

@@ -74,10 +74,12 @@ class InterfaceTemplateContextBuilder(object):
         name = '%s%s' % (v8_utilities.cpp_name(interface), 'Partial' if interface.is_partial else '')
 
         # Constructors
-        constructors = any(constructor.name == 'Constructor' for constructor in interface.constructors)
-        custom_constructors = interface.custom_constructors
-        html_constructor = 'HTMLConstructor' in interface.extended_attributes
-        has_constructor_callback = constructors or custom_constructors or html_constructor
+        has_constructor_callback = False
+        if not interface.is_partial:
+            constructors = any(constructor.name == 'Constructor' for constructor in interface.constructors)
+            custom_constructors = interface.custom_constructors
+            html_constructor = 'HTMLConstructor' in interface.extended_attributes
+            has_constructor_callback = constructors or custom_constructors or html_constructor
 
         attributes = []
         methods = []