feat(dir): default to ltr css, rtl overrides w/ [dir=rtl] selectors

Author: adamdbradley

core/src/themes/ionic.globals.scss

@@ -21,7 +21,7 @@
 @import "./ionic.mixins";
 
 // Global app direction
-$app-direction: ltr !default;
+$app-direction: null !default;
 
 
 // Global font path

core/src/themes/ionic.mixins.scss

@@ -158,6 +158,15 @@
   }
 }
 
+
+// Text Direction - ltr / rtl
+// $app-direction: multi | rtl | ltr | null (default)
+// multi: Both [dir=ltr] and [dir=rtl] are applied to css selectors.
+// rtl: Always assumes rtl and only includes rtl css. No [dir] selectors.
+// ltr: Always assumes ltr and only includes ltr css. No [dir] selectors.
+// null: CSS defaults to use the ltr css, and adds [dir=rtl] selectors to override ltr defaults.
+// ----------------------------------------------------------
+
 @mixin multi-dir() {
   @if $app-direction == multi {
     $root: #{&};
@@ -172,7 +181,7 @@
 }
 
 @mixin rtl() {
-  @if $app-direction == multi {
+  @if $app-direction == multi or $app-direction == null {
     $root: #{&};
     @at-root [dir="rtl"] {
       #{$root} {
@@ -192,7 +201,7 @@
         @content;
       }
     }
-  } @else if $app-direction == ltr {
+  } @else if $app-direction == ltr or $app-direction == null {
     @content;
   }
 }