bindings: Make the sequence conversion code more complaint with WebIDL.

third_party/WebKit/LayoutTests/storage/websql/execute-sql-args.js

 var throwOnToStringObject = { };
 throwOnToStringObject.toString = function () { throw "Cannot call toString on this object." };
 
 var throwOnGetLengthObject = { };
 throwOnGetLengthObject.__defineGetter__("length", function () { throw "Cannot get length of this object."; });
 
 var throwOnGetZeroObject = { length: 1 };
 throwOnGetZeroObject.__defineGetter__("0", function () { throw "Cannot get 0 property of this object."; });
 
+function createIterable(iterations) {
+    return {
+        [Symbol.iterator]() {
+            var i = 0;
+            return {next: () => iterations[i++]};
+        },
+    };
+}
+var emptyIterableObject = createIterable([{done: true}]);
+var singleItemIterableObject = createIterable([{done: false, value: "arg0"}, {done: true}]);
+
 var expectNoException = [
     'null',
     'undefined',
     '0',
     '""',
     '"", null',
     '"", undefined',
     '"", []',
     '"", [ "arg0" ]',
-    '"", { length: 0 }',
-    '"", { length: 1, 0: "arg0" }',
+    '"", emptyIterableObject',
+    '"", singleItemIterableObject',
     '"", null, null',
     '"", null, undefined',
     '"", null, function(){}',
     '"", null, null, null',
     '"", null, null, undefined',
     '"", null, null, function(){}',
 ];
 
 var expectException = [
     '',
     'throwOnToStringObject',
     '"", throwOnGetLengthObject',
     '"", throwOnGetZeroObject',
     '"", [ throwOnToStringObject ]',
     '"", 0',
     '"", ""',
     '"", { }',
+    '"", { length: 0 }',
+    '"", { length: 1, 0: "arg0" }',
     '"", null, 0',
     '"", null, ""',
     '"", null, { }',
     '"", null, null, 0',
     '"", null, null, ""',
     '"", null, null, { }',
 ];
 
 function tryExecuteSql(transaction, parameterList)
 {
@@ skipping 31 matching lines @@
     if (window.testRunner)
         testRunner.notifyDone();
 }
 
 function runTest()
 {
 
     var db = openDatabaseWithSuffix("ExecuteSQLArgsTest", "1.0", "Test of handling of the arguments to SQLTransaction.executeSql", 1);
     db.transaction(runTransactionTests);
 }