Migrate some tests to the new htmlRunner

Fix events.get_timeStamp (was events.get_timestamp, wrong casing).

Rename `newRunner` to `htmlRunner`.

move tests to src/tests (from src/browser/tests). src/runtime and possibly other
parts might want to have html tests too.

src/tests/encoding/decoder.html

@@ -0,0 +1,17 @@
+<script src="../testing.js"></script>
+<script id=decoder>
+  let d1 = new TextDecoder();
+  testing.expectEqual('utf-8', d1.encoding);
+  testing.expectEqual(false, d1.fatal);
+  testing.expectEqual(false, d1.ignoreBOM);
+
+  testing.expectEqual('𠮷', d1.decode(new Uint8Array([240, 160, 174, 183])));
+  testing.expectEqual('𠮷', d1.decode(new Uint8Array([0xEF, 0xBB, 0xBF, 240, 160, 174, 183])));
+  testing.expectEqual('<27>2', d1.decode(new Uint8Array([249, 50])));
+
+  let d2 = new TextDecoder('utf8', {fatal: true})
+  testing.expectError('Error: InvalidUtf8', () => {
+    let data  = new Uint8Array([240, 240, 160, 174, 183]);
+    d2.decode(data);
+  });
+</script>

src/tests/encoding/encoder.html

@@ -0,0 +1,13 @@
+<script src="../testing.js"></script>
+<script id=encoder>
+  var encoder = new TextEncoder();
+  testing.expectEqual('utf-8', encoder.encoding);
+  testing.expectEqual([226, 130, 172], Array.from(encoder.encode('€')));
+
+  // Invalid utf-8 sequence.
+  // Browsers give a different result for this, they decode it to:
+  //    50, 50, 54, 44, 52, 48, 44, 49, 54, 49
+  testing.expectError('Error: InvalidUtf8', () => {
+    encoder.encode(new Uint8Array([0xE2,0x28,0xA1]));
+  });
+</script>