🐛 Fix minimap position relying upon node order

Closes #358

lib/minimap-element.coffee

@@ -44,9 +44,8 @@ class MinimapElement extends HTMLElement
       'minimap.displayMinimapOnLeft': (displayMinimapOnLeft) =>
         swapPosition = @minimap? and displayMinimapOnLeft isnt @displayMinimapOnLeft
         @displayMinimapOnLeft = displayMinimapOnLeft
-        @classList.toggle('left', displayMinimapOnLeft and @absoluteMode)
 
-        @swapMinimapPosition() if swapPosition
+        @swapMinimapPosition()
 
       'minimap.minimapScrollIndicator': (@minimapScrollIndicator) =>
         if @minimapScrollIndicator and not @scrollIndicator?
@@ -76,7 +75,6 @@ class MinimapElement extends HTMLElement
 
       'minimap.absoluteMode': (@absoluteMode) =>
         @classList.toggle('absolute', @absoluteMode)
-        @classList.toggle('left', @displayMinimapOnLeft and @absoluteMode)
 
   # Internal: DOM callback invoked when a new {MinimapElement} is attached
   # to the DOM.
@@ -118,18 +116,18 @@ class MinimapElement extends HTMLElement
   # `displayMinimapOnLeft` setting.
   attach: ->
     return if @attached
+    @getTextEditorElementRoot().appendChild(this)
     @swapMinimapPosition()
     @attached = true
 
   # Attaches the {MinimapElement} to the left of the target {TextEditorElement}.
   attachToLeft: ->
-    root = @getTextEditorElementRoot()
-    root.insertBefore(this, root.children[0])
+    @classList.add('left')
 
   # Attaches the {MinimapElement} to the right of the target
   # {TextEditorElement}.
   attachToRight: ->
-    @getTextEditorElementRoot().appendChild(this)
+    @classList.remove('left')
 
   # Swaps the {MinimapElement} position based on the value of the
   # `displayMinimapOnLeft` setting.

spec/minimap-element-spec.coffee

@@ -644,7 +644,7 @@ describe 'MinimapElement', ->
     describe 'when minimap.displayMinimapOnLeft setting is true', ->
       it 'moves the attached minimap to the left', ->
         atom.config.set 'minimap.displayMinimapOnLeft', true
-        expect(Array::indexOf.call(editorElement.shadowRoot.children, minimapElement)).toEqual(0)
+        expect(minimapElement.classList.contains('left')).toBeTruthy()
 
       describe 'when the minimap is not attached yet', ->
         beforeEach ->
@@ -663,7 +663,7 @@ describe 'MinimapElement', ->
           minimapElement.attach()
 
         it 'moves the attached minimap to the left', ->
-          expect(Array::indexOf.call(editorElement.shadowRoot.children, minimapElement)).toEqual(0)
+          expect(minimapElement.classList.contains('left')).toBeTruthy()
 
     describe 'when minimap.adjustMinimapWidthToSoftWrap is true', ->
       [minimapWidth] = []
@@ -920,7 +920,6 @@ describe 'MinimapElement', ->
         describe 'when the displayMinimapOnLeft setting is enabled', ->
           beforeEach ->
             atom.config.set('minimap.displayMinimapOnLeft', true)
-            nextAnimationFrame()
 
           it 'adjusts the size of the control div to fit in the minimap', ->
             expect(controls.clientWidth).toEqual(minimapElement.canvas.clientWidth / devicePixelRatio)

styles/minimap.less

@@ -4,16 +4,25 @@ atom-notifications:empty {
   pointer-events: none
 }
 
+atom-text-editor::shadow .editor--private {
+  order: 2;
+}
+
 atom-text-editor::shadow, atom-text-editor {
   atom-text-editor-minimap {
     display: block;
     width: 10%;
     height: 100%;
     overflow: hidden;
     position: relative;
+    order: 2;
 
     -webkit-user-select: none;
 
+    &.left {
+      order: 1;
+    }
+
     &.absolute {
       position: absolute;
       right: 0;