fix: stop empty attrs on elements

Author: hperrin

packages/list/Item.svelte

@@ -9,7 +9,7 @@
     class:mdc-list-item--disabled={disabled}
     use:Ripple={[ripple, {unbounded: false, color}]}
     {href}
-    aria-current={activated ? 'page' : undefined}
+    {...(activated ? {'aria-current': 'page'} : {})}
     {tabindex}
     on:click={action}
     on:keydown={handleKeydown}
@@ -25,7 +25,7 @@
     class:mdc-list-item--selected={selected}
     class:mdc-list-item--disabled={disabled}
     use:Ripple={[ripple, {unbounded: false, color}]}
-    aria-current={activated ? 'page' : undefined}
+    {...(activated ? {'aria-current': 'page'} : {})}
     {tabindex}
     on:click={action}
     on:keydown={handleKeydown}
@@ -43,8 +43,8 @@
     class:mdc-menu-item--selected={role === 'menuitem' && selected}
     use:Ripple={[ripple, {unbounded: false, color}]}
     {role}
-    aria-selected={role === 'option' ? (selected ? 'true' : 'false') : undefined}
-    aria-checked={(role === 'radio' || role === 'checkbox') ? (checked ? 'true' : 'false') : undefined}
+    {...(role === 'option' ? {'aria-selected': (selected ? 'true' : 'false')} : {})}
+    {...((role === 'radio' || role === 'checkbox') ? {'aria-checked': (checked ? 'true' : 'false')} : {})}
     {tabindex}
     on:click={action}
     on:keydown={handleKeydown}

packages/slider/Slider.svelte

@@ -10,7 +10,7 @@
   aria-valuemin={min}
   aria-valuemax={max}
   aria-valuenow={value}
-  data-step={step === 0 ? undefined : step}
+  {...(step === 0 ? {} : {'data-step': step})}
   {tabindex}
   {...inputProps}
   on:MDCSlider:change={handleChange}