Merge pull request #15828 from atom/ns-clear-dimensions-cache

Clear the dimensions cache after updating the soft wrap column

src/text-editor-component.js

@@ -2118,6 +2118,7 @@ class TextEditorComponent {
       // rendered start row accurately. 😥
       this.populateVisibleRowRange(renderedStartRow)
       this.props.model.setEditorWidthInChars(this.getScrollContainerClientWidthInBaseCharacters())
+      this.derivedDimensionsCache = {}
 
       this.suppressUpdates = false
     }