LibWeb: Fix division by zero in table columns width distribution

If total max columns width (grid_max) is zero then available width
should be divided equally between columns. Previously there was
division by zero: `column.max_width / grid_max`.

Tests/LibWeb/Layout/input/table/zero-columns-gridmax.html

@@ -0,0 +1,15 @@
+<style>
+.table {
+    display: table;
+    width: 200px;
+}
+
+.row {
+    display: table-row;
+}
+
+.cell {
+    display: table-cell;
+}
+</style>
+<div class="table"><div class="row"><div class="cell"></div></div></div>