Simple Typescript: declare static property errors on build (but static declare works)

[dcporter]

Bug Report

Current Behavior

Building simple typescript with declare static properties fails. Switching to static declare succeeds. Both are valid TypeScript syntax. Prettier enforces declare static by default (which matches how I instinctively write it), fwiw.

Input Code

class Foo {
   declare static bar: string;
}

Expected behavior/code
It should compile. Instead I get the following error:

Error: Module build failed (from […]/node_modules/babel-loader/lib/index.js):
SyntaxError: […]/Foo.ts: Unexpected token (24:19)

  22 | 
  23 | class Foo {
> 24 |     declare static bar: string;
     |                    ^
  25 | }
  26 | 
  27 | 
    at Object.raise ([…]/node_modules/@babel/parser/lib/index.js:6983:17)
    at Object.unexpected ([…]/node_modules/@babel/parser/lib/index.js:8376:16)
    at Object.parseClassMemberWithIsStatic ([…]/node_modules/@babel/parser/lib/index.js:11615:12)
    at Object.parseClassMemberWithIsStatic ([…]/node_modules/@babel/parser/lib/index.js:5978:11)
    at Object.parseClassMember ([…]/node_modules/@babel/parser/lib/index.js:11508:10)
    at Object.parseClassMember ([…]/node_modules/@babel/parser/lib/index.js:5952:11)
    at […]/node_modules/@babel/parser/lib/index.js:11463:14
   [much more stack]

This feature was introduced in #10484.

Babel Configuration (babel.config.js, .babelrc, package.json#babel, cli command, .eslintrc)

The relevant bit: "@babel/plugin-transform-typescript", { allowDeclareFields: true }

Environment

  System:
    OS: macOS 10.15.3
  Binaries:
    Node: 12.14.1 - /usr/local/bin/node
    Yarn: 1.21.1 - /usr/local/bin/yarn
    npm: 6.13.4 - /usr/local/bin/npm
  Monorepos:
    Yarn Workspaces: 1.21.1
    Lerna: 2.11.0
  npmPackages:
    @babel/cli: ^7.6.4 => 7.7.0 
    @babel/plugin-proposal-class-properties: ^7.7.0 => 7.7.0 
    @babel/plugin-proposal-decorators: ^7.7.0 => 7.7.0 
    @babel/plugin-proposal-nullish-coalescing-operator: ^7.4.4 => 7.4.4 
    @babel/plugin-proposal-optional-chaining: ^7.7.5 => 7.7.5 
    @babel/preset-typescript: ^7.7.2 => 7.7.4 
    eslint: ^5.16.0 => 5.16.0 
    lerna: ^2.0.0 => 2.11.0 

[babel-bot]

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