Compiler doesn't resolve node dependency using "main" key value in package.json

[jmosney]

package.json can declare a key "main" with a value that's a reference to a file in the package (npm docs). However Google Closure Compiler seems to ignore that value and always look for a file "index.js" as the default. So when a file using that package declares a dependency using require, GCC throws an error.

Example

End user's project

index.js
const xtend = require('xtend');
package.json
{ "dependencies": { "xtend": "4.0.0" } }

npm project

immutable.js
... useful utility...

package.json
{ "main": "immutable" }

When the end user runs GCC (ensuring they've supplied the xtend package using the --js flag to the command) they will get this error:
my-project.js:1: ERROR - Failed to load module "xtend" var xtend = require('xtend'); ^ 1 error(s)

This is sort of related to #3149 (Packages with dir as "main" in package.json do not resolve.) but I'm filing it anyway just in case the solution for that bug doesn't address this.

I've patched xtend here to fix material-components-web compilation via GCC for my project (I pull in my fork via my package.json).

[EatingW]

Created Google internal issue b/120550812.

[ChadKillingsworth]

@jmosney Did you supply the package.json file to the compilation? You need to pass --js node_modules/immutable/package.json along with your other source files.

[jmosney]

Ah, that did it! Thanks very much Chad!