added type definitions for multireducer (#35776)

* added type definitions for multireducer

* added type definitions for multireducer fixed issues

types/multireducer/index.d.ts

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+// Type definitions for multireducer 3.1
+// Project: https://github.com/erikras/multireducer
+// Definitions by: Anthony M. Lee <https://github.com/immigration9>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.1
+
+export interface MetaObject {
+  [key: string]: string;
+}
+
+export interface ActionObject {
+  meta: MetaObject;
+  [rest: string]: any;
+}
+
+export function bindActionCreators(actions: any, dispatch: any, reducerKey: string): any;
+export function wrapDispatch(dispatch: any, reducerKey: string): any;
+export function wrapAction(action: any, reducerKey: string): ActionObject;
+
+export default function multireducer(reducers: { [key: string]: any }, reducerKey?: string): (state: any, action: any) => any;

types/multireducer/multireducer-tests.ts

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+import multireducer from 'multireducer';
+import { deepEqual } from 'assert';
+
+const initialState = { a: 1, b: 2, c: 3 };
+
+const first = (state = initialState, action = {}) => {
+  return { ...state, a: 10 };
+};
+
+const second = (state = initialState, action = {}) => {
+  return { ...state, b: 20 };
+};
+
+const third = (state = initialState, action = {}) => {
+  return { ...state, c: 30 };
+};
+
+const reducers = multireducer({ first, second, third })(undefined, {});
+
+const expectedResult = {
+  first: { a: 10, b: 2, c: 3 },
+  second: { a: 1, b: 20, c: 3 },
+  third: { a: 1, b: 2, c: 30 }
+};
+
+deepEqual(reducers, expectedResult);

types/multireducer/tsconfig.json

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+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictNullChecks": true,
+        "strictFunctionTypes": true,
+        "baseUrl": "../",
+        "typeRoots": [
+            "../"
+        ],
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "multireducer-tests.ts"
+    ]
+}

types/multireducer/tslint.json

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+{ "extends": "dtslint/dt.json" }