Fix really dumb mistake in Mac accessibility.

Missing braces when adding code inside an "if" block,
resulting in lots of attributes being marked as editable
when they shouldn't be, breaking VoiceOver.

Regression happened in:
https://crrev.com/6185ca046850b24b92a5dffd9ab7d1ecc3048001
https://codereview.chromium.org/1435113003/

BUG=559210,473220

Review URL: https://codereview.chromium.org/1473483002

Cr-Commit-Position: refs/heads/master@{#361235}

content/browser/accessibility/browser_accessibility_cocoa.mm

@@ -1949,10 +1949,12 @@ bool InitializeAccessibilityTreeSearch(
   if (!browserAccessibility_)
     return NO;
 
-  if ([attribute isEqualToString:NSAccessibilityFocusedAttribute])
+  if ([attribute isEqualToString:NSAccessibilityFocusedAttribute]) {
     if ([self internalRole] == ui::AX_ROLE_DATE_TIME)
       return NO;
     return GetState(browserAccessibility_, ui::AX_STATE_FOCUSABLE);
+  }
+
   if ([attribute isEqualToString:NSAccessibilityValueAttribute]) {
     return browserAccessibility_->GetBoolAttribute(
         ui::AX_ATTR_CAN_SET_VALUE);