Upgrade packages

`yarn upgrade-interactive` all the things.

Note that because the non-dev dependencies in the individual packages
are all locked to a specific version, I also ran `yarn outdated` to
identify those, and then:

    (cd packages/workspace-scripts && yarn add @babel/parser@7.4.2 @babel/runtime-corejs2@7.4.2 @babel/traverse@7.4.0)
    for X in babel-plugin-invariant-transform dedent delay delay event-emitter stable-stringify; do
      (cd packages/$X && yarn add @babel/runtime-corejs2@7.4.2)
    done

will evidently want to make a less manual way to do that via a script.

Includes tweaks in workspace-scripts/src/publish.ts to keep the new
version of TypeScript happy.

packages/babel-plugin-invariant-transform/package.json

@@ -34,6 +34,6 @@
   },
   "dependencies": {
     "@babel/core": "*",
-    "@babel/runtime-corejs2": "7.3.1"
+    "@babel/runtime-corejs2": "7.4.2"
   }
 }

packages/dedent/package.json

@@ -29,7 +29,7 @@
     "typecheck:ts": "workspace-scripts typecheck:ts"
   },
   "dependencies": {
-    "@babel/runtime-corejs2": "7.3.1"
+    "@babel/runtime-corejs2": "7.4.2"
   },
   "devDependencies": {
     "@wincent/workspace-scripts": "0.0.1"

packages/delay/package.json

@@ -29,7 +29,7 @@
     "typecheck:ts": "workspace-scripts typecheck:ts"
   },
   "dependencies": {
-    "@babel/runtime-corejs2": "7.3.1",
+    "@babel/runtime-corejs2": "7.4.2",
     "@wincent/invariant": "0.0.1"
   },
   "devDependencies": {

packages/event-emitter/package.json

@@ -29,7 +29,7 @@
     "typecheck:ts": "workspace-scripts typecheck:ts"
   },
   "dependencies": {
-    "@babel/runtime-corejs2": "7.3.1"
+    "@babel/runtime-corejs2": "7.4.2"
   },
   "devDependencies": {
     "@wincent/workspace-scripts": "0.0.1"

packages/stable-stringify/package.json

@@ -29,7 +29,7 @@
     "typecheck:ts": "workspace-scripts typecheck:ts"
   },
   "dependencies": {
-    "@babel/runtime-corejs2": "7.3.1",
+    "@babel/runtime-corejs2": "7.4.2",
     "@wincent/is-object": "0.0.1"
   },
   "devDependencies": {

packages/workspace-scripts/package.json

@@ -33,8 +33,8 @@
     "typecheck:ts": "./bin/index.js typecheck:ts"
   },
   "dependencies": {
-    "@babel/parser": "7.3.3",
-    "@babel/runtime-corejs2": "7.3.1",
-    "@babel/traverse": "7.2.3"
+    "@babel/parser": "7.4.2",
+    "@babel/runtime-corejs2": "7.4.2",
+    "@babel/traverse": "7.4.0"
   }
 }

packages/workspace-scripts/src/publish.ts

@@ -31,16 +31,23 @@ async function getPackageNames() {
 function runPrepublishChecks() {
   return new Promise((resolve, reject) => {
     const yarn = spawn('yarn', ['run', 'prepublish']);
+    if (!yarn.stderr || !yarn.stdout) {
+      throw new Error('spawn did not provide stderr and stdout');
+    }
+
     let stdout = '';
     let stderr = '';
+
     yarn.stderr.on('data', data => {
       stderr += data;
       print('.');
     });
+
     yarn.stdout.on('data', data => {
       stdout += data;
       print('.');
     });
+
     yarn.on('close', code => {
       if (code) {
         print.line(`\n${stdout}`);