Fix RNTesterUnitTests failure (#22658)
Fix RNTesterUnitTests failure (#22658)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/22658

Add JavaScriptCore.framework to RNTester's RNTesterUnitTests target. This resolves the failure seen when running `scripts/objc-test-ios.sh test` seen in Circle CI.

 See D9875409 for a related diff (https://github.com/facebook/react-native/commit/78fcf7c5598ce7f5d0d62110eb34fe5a4b962e71 in open source).

Without this diff, `scripts/objc-test-ios.sh test` would fail with the following error (see Circle https://circleci.com/gh/facebook/react-native/63704):

```
�  ld: symbol(s) not found for architecture x86_64

�  clang: error: linker command failed with exit code 1 (use -v to see invocation)

Testing failed:
	"_JSObjectGetPrototype", referenced from:
	"_JSObjectSetPrototype", referenced from:
	"_JSPropertyNameAccumulatorAddName", referenced from:
	"_JSObjectCopyPropertyNames", referenced from:
	"_JSContextGetGlobalObject", referenced from:
	"_JSValueMakeString", referenced from:
	"_JSValueIsNumber", referenced from:
	"_JSClassCreate", referenced from:
	"_JSObjectGetPropertyAtIndex", referenced from:
	"_JSObjectMakeArray", referenced from:
	"_JSEvaluateScript", referenced from:
	"_JSValueIsUndefined", referenced from:
	"_JSPropertyNameArrayGetCount", referenced from:
	"_JSPropertyNameArrayGetNameAtIndex", referenced from:
	"_JSPropertyNameArrayRelease", referenced from:
	"_JSValueMakeUndefined", referenced from:
	"_JSValueMakeNull", referenced from:
	"_JSStringCreateWithUTF8CString", referenced from:
	"_JSObjectSetProperty", referenced from:
	"_JSObjectHasProperty", referenced from:
	"_kJSClassDefinitionEmpty", referenced from:
	"_JSObjectIsFunction", referenced from:
	"_JSValueIsBoolean", referenced from:
	"_JSValueIsInstanceOfConstructor", referenced from:
	"_JSValueIsObjectOfClass", referenced from:
	"_JSValueToNumber", referenced from:
	"_JSGlobalContextRelease", referenced from:
	"_JSValueToBoolean", referenced from:
	"_JSValueIsArray", referenced from:
	"_JSValueMakeNumber", referenced from:
	"_JSObjectSetPrivate", referenced from:
	"_JSValueIsNull", referenced from:
	"_JSObjectSetPropertyAtIndex", referenced from:
	"_JSValueIsObject", referenced from:
	"_JSValueMakeBoolean", referenced from:
	"_JSValueUnprotect", referenced from:
	"_JSValueToStringCopy", referenced from:
	"_JSObjectGetProperty", referenced from:
	"_JSValueToObject", referenced from:
	"_JSObjectGetPrivate", referenced from:
	"_JSStringRelease", referenced from:
	"_JSGlobalContextRetain", referenced from:
	"_JSStringIsEqual", referenced from:
	"_JSStringGetMaximumUTF8CStringSize", referenced from:
	"_JSObjectCallAsFunction", referenced from:
	"_JSStringGetUTF8CString", referenced from:
	"_JSValueProtect", referenced from:
	"_JSValueIsString", referenced from:
	"_JSStringRetain", referenced from:
	"_JSObjectMake", referenced from:
	"_JSGlobalContextCreateInGroup", referenced from:
	"_JSObjectCallAsConstructor", referenced from:
	Linker command failed with exit code 1 (use -v to see invocation)
	Testing cancelled because the build failed.
** TEST FAILED **
```

Reviewed By: fkgozali

Differential Revision: D13474936

fbshipit-source-id: b12ddd6dcb95a7a588463d74cc0798dd591bdd78

hammerandchisel/react-native,janicduplessis/react-native,arthuralee/react-native,hoangpham95/react-native,exponentjs/react-native,exponentjs/react-native,facebook/react-native,exponent/react-native,pandiaraj44/react-native,javache/react-native,exponent/react-native,pandiaraj44/react-native,facebook/react-native,exponent/react-native,hammerandchisel/react-native,pandiaraj44/react-native,javache/react-native,janicduplessis/react-native,arthuralee/react-native,exponent/react-native,hoangpham95/react-native,pandiaraj44/react-native,janicduplessis/react-native,janicduplessis/react-native,hoangpham95/react-native,exponent/react-native,exponent/react-native,myntra/react-native,hoangpham95/react-native,hammerandchisel/react-native,javache/react-native,myntra/react-native,exponent/react-native,exponentjs/react-native,javache/react-native,exponent/react-native,javache/react-native,hammerandchisel/react-native,hoangpham95/react-native,javache/react-native,facebook/react-native,facebook/react-native,javache/react-native,myntra/react-native,myntra/react-native,exponentjs/react-native,facebook/react-native,myntra/react-native,pandiaraj44/react-native,arthuralee/react-native,hammerandchisel/react-native,hammerandchisel/react-native,pandiaraj44/react-native,arthuralee/react-native,pandiaraj44/react-native,hammerandchisel/react-native,facebook/react-native,janicduplessis/react-native,hammerandchisel/react-native,facebook/react-native,exponentjs/react-native,javache/react-native,myntra/react-native,janicduplessis/react-native,myntra/react-native,hoangpham95/react-native,facebook/react-native,arthuralee/react-native,javache/react-native,janicduplessis/react-native,facebook/react-native,janicduplessis/react-native,myntra/react-native,hoangpham95/react-native,exponentjs/react-native,exponentjs/react-native,exponentjs/react-native,hoangpham95/react-native,pandiaraj44/react-native,myntra/react-native