[dialog] Fix <cr-drawer> default styles.

Due to a HTML specification change, the default UA stylesheet for modal
dialog elements has changed:
https://github.com/whatwg/html/pull/5936/files
https://chromium.googlesource.com/chromium/src/+/be7281e188f22856bf9084d9f5c74a0f48eee1da

Specifically for this bug max-width/max-height were set. This change
explicitly resets the style for max-width/max-height to their initial
values.

Bug: 1148225
Change-Id: Ibf62fea46fc78206df4da240b1fb44f923b07415
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2538332Reviewed-by: calamity <calamity@chromium.org>
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827685}

ui/webui/resources/cr_elements/cr_drawer/cr_drawer.html

@@ -16,6 +16,8 @@
         bottom: 0;
         left: calc(-1 * var(--drawer-width));
         margin: 0;
+        max-height: initial;
+        max-width: initial;
         overflow: hidden;
         padding: 0;
         position: absolute;