Updating intersect & loading cell placeholders (issues #118 & #119)

Previously the "intersect frame" cells were displaying the character
'X' as their content. We have changed it so they display their actual
data values now.

Additionally, we are changing unloaded cell displays from being the
text 'undefined' to being '...'

object_database/web/content/webcomponents/sheet/src/PrimaryFrame.js

@@ -192,7 +192,11 @@ class PrimaryFrame extends TableElementsFrame {
         if(!this.lockedFramesIntersect.isEmpty){
             this.lockedFramesIntersect.forEachPoint(aPoint => {
                 let value = this.dataFrame.getAt(aPoint);
-                this.innerElementAt(aPoint).innerText = 'x';
+                if(value == undefined){
+                    this.setTextContentAt(aPoint, '...');
+                } else {
+                    this.setTextContentAt(aPoint, value.toString());
+                }
             });
         }
     }
@@ -215,7 +219,7 @@ class PrimaryFrame extends TableElementsFrame {
                 if(dataValue != undefined){
                     this.setTextContentAt(translation, dataValue.toString());
                 } else {
-                    this.setTextContentAt(translation, 'undefined');
+                    this.setTextContentAt(translation, '...');
                 }
                 element.setAttribute('data-relative-x', aPoint.x);
                 element.setAttribute('data-relative-y', aPoint.y);
@@ -246,7 +250,7 @@ class PrimaryFrame extends TableElementsFrame {
                 if(dataValue != undefined){
                     this.setTextContentAt(translation, dataValue.toString());
                 } else {
-                    this.setTextContentAt(translation, 'undefined');
+                    this.setTextContentAt(translation, '...');
                 }
                 element.setAttribute('data-relative-x', aPoint.x);
                 element.setAttribute('data-relative-y', aPoint.y);
@@ -274,7 +278,7 @@ class PrimaryFrame extends TableElementsFrame {
             if(value != undefined){
                 this.setTextContentAt(translation, value.toString());
             } else {
-                this.setTextContentAt(translation, 'undefined');
+                this.setTextContentAt(translation, '...');
             }
             element.setAttribute('data-relative-x', aPoint.x);
             element.setAttribute('data-relative-y', aPoint.y);