Make sure all methods have a correct name.

Adds an assertion to idlharness to check the name attribute of
methods, and fixes the bindings code to make sure we actually set the
name correctly.

Bug: 1106097, 1097814
Change-Id: I73dea7b96a94a9b2925c23156e6ef8146291cbc9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2300824
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789135}

resources/idlharness.js

@@ -2534,6 +2534,10 @@ IdlInterface.prototype.do_member_operation_asserts = function(memberHolderObject
         memberHolderObject[member.name].length,
         minOverloadLength(ctors),
         "property has wrong .length");
+    assert_equals(
+        memberHolderObject[member.name].name,
+        member.name,
+        "property has wrong .name");
 
     // Make some suitable arguments
     var args = member.arguments.map(function(arg) {