Set maximum decimal places to 1 in human readable delta

1.234 is confusing since the dot might be confused for a comma. Switch
to limiting fractional digits to just 1 decimal place.

Change-Id: If9a568821e3fda3ce58651e2355deaab02064ef4
diff --git a/web/chromium-binary-size.ts b/web/chromium-binary-size.ts
index 0cf14bd..01e986c 100644
--- a/web/chromium-binary-size.ts
+++ b/web/chromium-binary-size.ts
@@ -288,7 +288,7 @@
       );
       const abs_delta = Math.abs(delta);
       const maybePlus = delta > 0 ? '+' : '';
-      const fmtr = Intl.NumberFormat('en-US', {maximumSignificantDigits: 4});
+      const fmtr = Intl.NumberFormat('en-US', { maximumFractionDigits: 1});
       if (abs_delta < 1024) {
         return '(' + maybePlus + delta + ' B)';
       } else if (abs_delta < 1024 * 1024) {
diff --git a/web/chromium-binary-size_test.ts b/web/chromium-binary-size_test.ts
index 56d393f..d4fb267 100644
--- a/web/chromium-binary-size_test.ts
+++ b/web/chromium-binary-size_test.ts
@@ -686,7 +686,7 @@
     // 2226000/1024/1024 = 2.12287902832
     assert.strictEqual(
       fetcher.getHumanReadableDelta('-2,226,000 bytes'),
-      '(-2.123 MiB)'
+      '(-2.1 MiB)'
     );
   });
 });