fix(DASH): Update dash manifest when minimumUpdatePeriod = 0 (#6187)

Fixes #6185

Backported to v4.3.x

lib/dash/dash_parser.js

@@ -1442,7 +1442,7 @@ shaka.dash.DashParser = class {
     // An attribute which is present and set to 0 should still result in
     // periodic updates.  For more, see:
     // https://github.com/Dash-Industry-Forum/Guidelines-TimingModel/issues/48
-    if (this.updatePeriod_ <= 0) {
+    if (this.updatePeriod_ < 0) {
       return;
     }
 

test/dash/dash_parser_live_unit.js

@@ -607,6 +607,23 @@ describe('DashParser Live', () => {
     expect(onError).toHaveBeenCalledTimes(1);
   });
 
+  it('still updates when @minimumUpdatePeriod is zero', async () => {
+    const lines = [
+      '<SegmentTemplate startNumber="1" media="s$Number$.mp4" duration="2" />',
+    ];
+    // updateTime parameter sets @minimumUpdatePeriod in the manifest.
+    const manifestText = makeSimpleLiveManifestText(lines, /* updateTime= */ 0);
+
+    /** @type {!jasmine.Spy} */
+    const tickAfter = updateTickSpy();
+    Date.now = () => 0;
+
+    fakeNetEngine.setResponseText('dummy://foo', manifestText);
+    await parser.start('dummy://foo', playerInterface);
+
+    expect(tickAfter).toHaveBeenCalledTimes(1);
+  });
+
   it('uses @minimumUpdatePeriod', async () => {
     const lines = [
       '<SegmentTemplate startNumber="1" media="s$Number$.mp4" duration="2" />',