When typing Korean, the last composition letter typed to InputField is omitted when User query "GetComponent<InputField>().text". Typing "개개개개개" or other symbols and pressing Enter the value that is printed to the console is "개개개개", and the last "개" just disappears from the InputField. When User selects the Text from InputField and tries typing more Korean letters He gets errors "ArgumentOutOfRangeExceptions: Cannot be negative." The User tried appending Input.compositionString to the text, but that doesn't help.

To reproduce:

1. Download project from the attached link and open in Unity
2. Open "SampleScene" scene
3. Enter Play mode
4. Type "개개개개개" or "내내내내내" (Type "rororororo" or "sososososo" with Korean IME enabled), and then press Enter
5. Observe that Console will only print "개개개개" or "내내내내". And the last character "개" or "내" will disappear from InputField

To reproduce from a scratch:

1. Open Unity and create a new project
2. In an empty scene, create an InputField.
3. Attach this simple script to InputField:

"public void OnEndEdit() {
print(GetComponent<InputField>().text);
}"

4. In Inspector, set InputField's "On End Edit" to the script's OnEndEdit() function
5. Enter Play mode
6. Type "개개개개개" or "내내내내내" (Type "rororororo" or "sososososo" with Korean IME enabled), and then press Enter
7. Observe that Console will only print "개개개개" or "내내내내". And the last character "개" or "내" will disappear from InputField

Notes:
- Project download link is in Comments section
- This issue appears only on OSX
- Could not check if this issue reproduces on Windows because https://issuetracker.unity3d.com/issues/unity-does-not-support-korean-input-in-the-editor issue blocks testing
- Clicking on the InputField to select the currently-typed letters and then trying to type "개개개개" or "내내내내" again spams multiple "ArgumentOutOfRangeExceptions: Cannot be negative" errors in the Console

Reproduced on Unity 2017.1.5f1, 2017.2.3p3, 2017.3.2f1, 2017.4.9f1, 2018.1.9f1, 2018.2.5f1 and 2018.3.0a9