Revert "Remove legacy iterator protocol use in Zotero.DB"

Reverting this until we can use Fx60 for testing.

This reverts commit dfe412d448.

chrome/content/zotero/xpcom/db.js

@@ -584,18 +584,22 @@ Zotero.DBConnection.prototype.queryAsync = Zotero.Promise.coroutine(function* (s
 		}
 		var failed = false;
 		if (options && options.onRow) {
-			// Wrap onRow to cancel iteration by default and reject the promise
-			// on any error, which Sqlite.jsm does not do.
-			onRow = function (row, cancel) {
+			// Errors in onRow don't stop the query unless StopIteration is thrown
+			onRow = function (row) {
 				try {
-					options.onRow(row, () => {
-						Zotero.debug("Query cancelled", 3);
-						cancel();
-					});
+					options.onRow(row);
 				}
 				catch (e) {
-					failed = e;
-					cancel();
+					// If the onRow throws a StopIteration, stop gracefully
+					if (e instanceof StopIteration) {
+						Zotero.debug("Query cancelled", 3);
+					}
+					// Otherwise, mark the promise as rejected, which Sqlite.jsm doesn't do
+					// on a StopIteration by default
+					else {
+						failed = e;
+					}
+					throw StopIteration;
 				}
 			}
 		}

test/tests/dbTest.js

@@ -151,16 +151,16 @@ describe("Zotero.DB", function() {
 			assert.equal(e.message, "Failed");
 		});
 		
-		it("should stop gracefully if onRow is cancelled", function* () {
+		it("should stop gracefully if onRow throws a StopIteration", function* () {
 			var i = 0;
 			var rows = [];
 			yield Zotero.DB.queryAsync(
 				"SELECT * FROM " + tmpTable,
 				false,
 				{
-					onRow: function (row, cancel) {
+					onRow: function (row) {
 						if (i > 0) {
-							return cancel();
+							throw StopIteration;
 						}
 						rows.push(row.getResultByIndex(0));
 						i++;