Allow for approximate equality in range-util tests

Several tests in range-util-test.js started failing locally after the
most recent Puppeteer upgrade with actual and expected values differing
by up to 1.0.

Change the tests to check for approximate equality, which is all that is
required for this use case.

src/annotator/test/range-util-test.js

@@ -133,17 +133,18 @@ describe('annotator.range-util', () => {
       selection.collapseToEnd();
       selection.extend(testNode, 0);
       const rect = rangeUtil.selectionFocusRect(selection);
-      assert.equal(rect.left, testNode.offsetLeft);
-      assert.equal(rect.top, testNode.offsetTop);
+      assert.approximately(rect.left, testNode.offsetLeft, 1);
+      assert.approximately(rect.top, testNode.offsetTop, 1);
     });
 
     it("returns the last line's rect if the selection is forwards", () => {
       selectNode(testNode);
       const rect = rangeUtil.selectionFocusRect(selection);
-      assert.equal(rect.left, testNode.offsetLeft);
-      assert.equal(
+      assert.approximately(rect.left, testNode.offsetLeft, 1);
+      assert.approximately(
         rect.top + rect.height,
-        testNode.offsetTop + testNode.offsetHeight
+        testNode.offsetTop + testNode.offsetHeight,
+        1
       );
     });
   });