[IMP] website_animate: hide horizontal scrollbar during animation

Before this commit, when animated elements with a css translate
overflowed the #wrapwrap (before and during animations), a horizontal
scrollbar was visible on the #wrapwrap until the end of the animation.

After this commit, the horizontal scrollbar is no longer visible at
any time during the animations.

task-2215118

closes odoo/design-themes#469

X-original-commit: 22e83be4f3
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

website_animate/static/src/scss/o_animate_frontend.scss

@@ -10,10 +10,17 @@
     backface-visibility: hidden; // avoid flickering
     text-rendering: geometricPrecision; // take care of animated titles
     visibility: hidden;
+
+    &:not(.o_animating) {
+        transform: none !important;
+    }
 }
 .o_animate_preview {
     visibility: visible;
 }
+.o_wanim_overflow_x_hidden {
+    overflow-x: hidden !important;
+}
 
 @-moz-keyframes o_animate_timeline_duration {
     0% { width: 0; }