Make null falsey.

test/logical_operator/or.wren

@@ -0,0 +1,20 @@
+// Note: These tests implicitly depend on ints being truthy.
+//       Also rely on IO.print() returning its argument.
+
+// Return the first true argument.
+IO.print(1 || true) // expect: 1
+IO.print(false || 1) // expect: 1
+IO.print(false || false || true) // expect: true
+
+// Return the last argument if all are false.
+IO.print(false || false) // expect: false
+IO.print(false || false || false) // expect: false
+
+// Short-circuit at the first true argument.
+IO.print(false) || // expect: false
+    IO.print(true) || // expect: true
+    IO.print(true) // should not print
+
+// Swallow a trailing newline.
+IO.print(true ||
+    true) // expect: true