Use CSS min-height to ensure gutter covers whole view

Issue codemirror#3884

Author: marijnh

lib/codemirror.css

@@ -191,6 +191,7 @@ div.CodeMirror span.CodeMirror-nonmatchingbracket {color: #f22;}
 
 .CodeMirror-gutters {
   position: absolute; left: 0; top: 0;
+  min-height: 100%;
   z-index: 3;
 }
 .CodeMirror-gutter {

lib/codemirror.js

@@ -763,8 +763,8 @@
       updateHeightsInViewport(cm);
       var barMeasure = measureForScrollbars(cm);
       updateSelection(cm);
-      setDocumentHeight(cm, barMeasure);
       updateScrollbars(cm, barMeasure);
+      setDocumentHeight(cm, barMeasure);
     }
 
     update.signal(cm, "update", cm);
@@ -781,17 +781,16 @@
       postUpdateDisplay(cm, update);
       var barMeasure = measureForScrollbars(cm);
       updateSelection(cm);
-      setDocumentHeight(cm, barMeasure);
       updateScrollbars(cm, barMeasure);
+      setDocumentHeight(cm, barMeasure);
       update.finish();
     }
   }
 
   function setDocumentHeight(cm, measure) {
     cm.display.sizer.style.minHeight = measure.docHeight + "px";
     cm.display.heightForcer.style.top = measure.docHeight + "px";
-    cm.display.gutters.style.height = Math.max(measure.docHeight + cm.display.barHeight + scrollGap(cm),
-                                               measure.clientHeight) + "px";
+    cm.display.gutters.style.height = (measure.docHeight + cm.display.barHeight + scrollGap(cm)) + "px";
   }
 
   // Read the actual heights of the rendered lines, and update their
@@ -3116,10 +3115,10 @@
 
     if (op.preparedSelection)
       cm.display.input.showSelection(op.preparedSelection);
-    if (op.updatedDisplay)
-      setDocumentHeight(cm, op.barMeasure);
     if (op.updatedDisplay || op.startHeight != cm.doc.height)
       updateScrollbars(cm, op.barMeasure);
+    if (op.updatedDisplay)
+      setDocumentHeight(cm, op.barMeasure);
 
     if (op.selectionChanged) restartBlink(cm);