This test verifies that formatBlock adds the containing block element's inline style to the block-style element that replaces it.

Before FormatBlock:
| "
"
| <div>
|   style="color: green"
|   "<#selection-anchor>hello<#selection-focus>"
| "
"

After FormatBlock:
| "
"
| <h1>
|   style="color: green"
|   "<#selection-anchor>hello<#selection-focus>"
| "
"

Before FormatBlock:
| "
"
| <div>
|   style="color: green"
|   <#selection-caret>
|   <br>
| "
"

After FormatBlock:
| "
"
| <h1>
|   style="color: green"
|   <#selection-caret>
|   <br>
| "
"

Before FormatBlock:
| "
"
| <span>
|   style="color: green"
|   "<#selection-anchor>hello<#selection-focus>"
| "
"

After FormatBlock:
| "
"
| <h1>
|   <span>
|     style="color: green"
|     "<#selection-anchor>hello<#selection-focus>"