TypeError raised by forbid-prop-types

[tinder-devon-strawn]

Seems to be introduced in 7.20.1, probably caused by #2676

checkProperties() in forbid-prop-types.js throws an error when declarations arg is undefined:

TypeError: Cannot read property 'forEach' of undefined
    at checkProperties (/Users/devons/Projects/scratch/node_modules/eslint-plugin-react/lib/rules/forbid-prop-types.js:95:20)
    at CallExpression (/Users/devons/Projects/scratch/node_modules/eslint-plugin-react/lib/rules/forbid-prop-types.js:185:11)
    at /Users/devons/Projects/scratch/node_modules/eslint/lib/util/safe-emitter.js:47:58
    at Array.forEach (<anonymous>)
    at Object.emit (/Users/devons/Projects/scratch/node_modules/eslint/lib/util/safe-emitter.js:47:38)
    at NodeEventGenerator.applySelector (/Users/devons/Projects/scratch/node_modules/eslint/lib/util/node-event-generator.js:251:26)
    at NodeEventGenerator.applySelectors (/Users/devons/Projects/scratch/node_modules/eslint/lib/util/node-event-generator.js:280:22)
    at NodeEventGenerator.enterNode (/Users/devons/Projects/scratch/node_modules/eslint/lib/util/node-event-generator.js:294:14)
    at CodePathAnalyzer.enterNode (/Users/devons/Projects/scratch/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:608:23)
    at Traverser.enter [as _enter] (/Users/devons/Projects/scratch/node_modules/eslint/lib/linter.js:865:28)

[ljharb]

Duplicate of #2682; fix will be released later today.