fix: upgrade to newer istanbul-lib-instrument, with fixes for inferred function names (#479)

Author: bcoe

package.json

@@ -84,7 +84,7 @@
     "glob": "^7.0.6",
     "istanbul-lib-coverage": "^1.0.0",
     "istanbul-lib-hook": "^1.0.0-alpha.4",
-    "istanbul-lib-instrument": "^1.3.1",
+    "istanbul-lib-instrument": "^1.4.0-candidate.0",
     "istanbul-lib-report": "^1.0.0-alpha.3",
     "istanbul-lib-source-maps": "^1.1.0",
     "istanbul-reports": "^1.0.0",
@@ -95,9 +95,9 @@
     "resolve-from": "^2.0.0",
     "rimraf": "^2.5.4",
     "signal-exit": "^3.0.1",
-    "spawn-wrap": "^1.3.4",
+    "spawn-wrap": "1.2.4",
     "test-exclude": "^3.3.0",
-    "yargs": "^6.4.0",
+    "yargs": "^6.6.0",
     "yargs-parser": "^4.0.2"
   },
   "devDependencies": {