The preview pane displays the wrong context menu inside code blocks

Prerequisites

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Description

The wrong context menu is sometimes displayed by the Markdown Preview pane. The function highlightCodeBlocks in renderer.coffee renders preformatted HTML blocks by creating instances of TextEditor and inserting them into the DOM. However, these TextEditor instances are not managed as Pane items. Instead, Workspace.getActivePaneItem() returns an instance of MarkdownPreviewView. Consequently, Workspace.getActiveTextEditor() returns undefined to the menu-item handlers.

Steps to Reproduce

Open a markdown file
Create a code block or HTML <pre> element with some content
Toggle Markdown-Preview
In the preview pane, right-click inside the code block

Expected behavior: The .markdown-preview context-menu should be displayed.

Actual behavior: The atom-text-editor context-menu is displayed.

Reproduces how often: Always

Versions

`atom --version`	`apm --version`	OS release
Atom : 1.34.0 Electron: 2.0.16 Chrome : 61.0.3163.100 Node : 8.9.3	apm 2.1.3 npm 6.2.0 node 8.9.3 x64 atom 1.34.0 python 2.7.12 git 2.7.4	Linux Mint 18.3

Additional Information

I believe this defect was introduced by pull #544, "Always use the text editor to highlight code blocks".
An example, showing edit commands enabled in the preview pane:

atom / markdown-preview