quill-lms: Fix property 'content' does not exist on type 'HTMLElement'
quill-lms: Fix property 'content' does not exist on type 'HTMLElement'

document.getElementsByName() returns a HTMLElement object, which does not have a property
'content'. [0]

TypeScript is typesafe, so where returned object HTMLElement does not have a property,
any attempted access to it will be invalid. Reported by tslint and typescript@2.9.2.

There are two potential solutions:

 - Utilize the generic .getAttribute('content'); or

 - Cast to the specific subtype (e.g. HTMLMetaElement) [1]  which does have
   a property 'content'.

tslint error:

  ERROR in [at-loader] ./app/modules/apollo.ts:16:113
    TS2339: Property 'content' does not exist on type 'HTMLElement'.

[0] https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement
[1] https://developer.mozilla.org/en-US/docs/Web/API/HTMLMetaElement

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