Block conflict with multiple plugins

[Jinhui]

Summary

Always return 1 plugin when use multiple plugins with the same block.

• HonKit version: 5.1.4

Step to reproduce

1. npm install package: honkit-plugin-prism and gitbook-plugin-mermaid-wnew
2. use the plugin in book.json

{
    "plugins": [
        "mermaid-wnew",
        "prism"
    ]
}

3. set debug point to listBlocks, then you will see it will always return the first plugin for code block

Expected results

• will generate the svg for mermaid code block
• will highlight other code block

Actual results

always do the first plugin for the same block:

• if mermaid-wnew before prism, it will generate the svg but all other code block will miss the highlight
• if prism before mermaid-wnew, all the other code block will highlight but will not generate svg