android, unicode urls: Fix correct url not passed to custom tabs.

[jainkuniya]

Before getFullUrl was adding realm even if unicode url string
starts with http. This issue is completely wired. It can not be
reproducible when remote debugger is on, on Android, but can
otherwise.

Replacing startsWith with indexOf doesn't make any logically
change, but have internal implementation difference. Thus this got
fixed.

[jainkuniya]

@gnprice @borisyankov this is also ready to review.

[borisyankov]

Sounds logical that this could be a fix.
Do you happen to have found this issue described or discussed somewhere online?
Would be a good addition to the commit message and would also make it more clear that this is the right fix.

[gnprice]

Hmm. Can you say more about exactly what you observed?

The theory in this commit appears to be that String.prototype.startsWith, in the JS environment that RN pulls in, has a bug that can cause it to give a completely wrong answer.

There's a programming cliché that "it's never a compiler bug":
https://blog.plover.com/prog/compiler-error.html
https://blog.codinghorror.com/the-first-rule-of-programming-its-always-your-fault/
The cliché applies equally well to the OS, to the Android platform and iOS SDK... and to the JS standard library. 🙂

Compilers do have bugs! And so do JS standard-library implementations, I'm sure. But these are systems a lot of people have banged on and a lot of people have put good work into making solid -- and so when you're tempted to say it's a compiler bug, or a JS stdlib bug, it's generally much more likely to be your bug, or something you don't understand yet.

And on the rare occasion you do find a JS stdlib bug... you'll want to have it well documented! So the path to resolving the situation well is basically the same either way.

[borisyankov]

The most likely place this bug can be is in the polyfill:

Libraries/polyfills/String.prototype.es6.js

[borisyankov]

... or more likely a JSC issue!

Very interesting thread here:
facebook/react-native#11370

Looks like JSC will be upgraded in RN 0.59
facebook/react-native#19737

And that would be a very likely fix for our issue.

[jainkuniya]

Let's close this. As I am not able to reproduce the issue. And there is no report for any such or similar issue from users. I am actively testing this and re-open it, if this is still a issue.

Actually the issue was only on Android, startsWith was not working as intendant.