Ensure .lines div is always at least the height of the scroll view

This ensures that the wrap guide extends the entire height of the
editor.

spec/editor-component-spec.coffee

@@ -90,6 +90,14 @@ describe "EditorComponent", ->
       expect(component.lineNodeForScreenRow(3).offsetTop).toBe 3 * lineHeightInPixels
       expect(component.lineNodeForScreenRow(4).offsetTop).toBe 4 * lineHeightInPixels
 
+    it "renders the .lines div at the full height of the editor if there aren't enough lines to scroll vertically", ->
+      editor.setText('')
+      node.style.height = '300px'
+      component.measureHeightAndWidth()
+
+      linesNode = node.querySelector('.lines')
+      expect(linesNode.offsetHeight).toBe 300
+
     describe "when showInvisibles is enabled", ->
       invisibles = null
 

src/editor-component.coffee

@@ -42,6 +42,7 @@ EditorComponent = React.createClass
       scrollWidth = editor.getScrollWidth()
       scrollTop = editor.getScrollTop()
       scrollLeft = editor.getScrollLeft()
+      scrollViewHeight = editor.getHeight()
       lineHeightInPixels = editor.getLineHeight()
       horizontalScrollbarHeight = editor.getHorizontalScrollbarHeight()
       verticalScrollbarWidth = editor.getVerticalScrollbarWidth()
@@ -64,7 +65,7 @@ EditorComponent = React.createClass
         scrollTop, scrollLeft, scrollHeight, scrollWidth, @scrollingVertically,
         @cursorsMoved, @selectionChanged, @selectionAdded, cursorBlinkPeriod,
         cursorBlinkResumeDelay, @onInputFocused, @onInputBlurred, @mouseWheelScreenRow,
-        invisibles
+        invisibles, scrollViewHeight
       }
 
       ScrollbarComponent

src/editor-scroll-view-component.coffee

@@ -17,7 +17,7 @@ EditorScrollViewComponent = React.createClass
 
   render: ->
     {editor, fontSize, fontFamily, lineHeight, showIndentGuide, invisibles} = @props
-    {renderedRowRange, pendingChanges, scrollTop, scrollLeft, scrollHeight, scrollWidth, scrollingVertically, mouseWheelScreenRow} = @props
+    {renderedRowRange, pendingChanges, scrollTop, scrollLeft, scrollHeight, scrollWidth, scrollViewHeight, scrollingVertically, mouseWheelScreenRow} = @props
     {selectionChanged, selectionAdded, cursorBlinkPeriod, cursorBlinkResumeDelay, cursorsMoved, onInputFocused, onInputBlurred} = @props
 
     if @isMounted()
@@ -37,7 +37,8 @@ EditorScrollViewComponent = React.createClass
       LinesComponent {
         ref: 'lines', editor, fontSize, fontFamily, lineHeight, showIndentGuide,
         renderedRowRange, pendingChanges, scrollTop, scrollLeft, scrollingVertically,
-        selectionChanged, scrollHeight, scrollWidth, mouseWheelScreenRow, invisibles
+        selectionChanged, scrollHeight, scrollWidth, mouseWheelScreenRow, invisibles,
+        scrollViewHeight
       }
 
   componentDidMount: ->

src/lines-component.coffee

@@ -15,9 +15,10 @@ LinesComponent = React.createClass
 
   render: ->
     if @isMounted()
-      {editor, scrollTop, scrollLeft, scrollHeight, scrollWidth, lineHeight} = @props
+      {editor, scrollTop, scrollLeft, scrollHeight, scrollWidth, lineHeight, scrollViewHeight} = @props
+
       style =
-        height: scrollHeight
+        height: Math.max(scrollHeight, scrollViewHeight)
         width: scrollWidth
         WebkitTransform: "translate3d(#{-scrollLeft}px, #{-scrollTop}px, 0px)"
 
@@ -35,7 +36,10 @@ LinesComponent = React.createClass
 
   shouldComponentUpdate: (newProps) ->
     return true if newProps.selectionChanged
-    return true unless isEqualForProperties(newProps, @props,  'renderedRowRange', 'fontSize', 'fontFamily', 'lineHeight', 'scrollTop', 'scrollLeft', 'showIndentGuide', 'scrollingVertically', 'invisibles')
+    return true unless isEqualForProperties(newProps, @props,
+      'renderedRowRange', 'fontSize', 'fontFamily', 'lineHeight', 'scrollTop', 'scrollLeft',
+      'showIndentGuide', 'scrollingVertically', 'invisibles', 'scrollViewHeight'
+    )
 
     {renderedRowRange, pendingChanges} = newProps
     for change in pendingChanges