To reproduce:

1. Download and open attached "repro960409.zip" project.
2. Open "bug" scene and enter play mode.
3. Notice outputted information in the text field or in the Console.
4. Build and run the project on WebGL, Android or iOS with any level stripping enabled.
5. Notice that outputted information of built project differs from output in the editor.

Expected result: Information output is the same in WebGL player as in the editor.
Actual result: AnimationCurve data is removed when project is built with WebGL.

Reproduced with: 2018.1.0a1, 2017.3.0b5, 2017.2.0f3. 2017.1.2p1, 5.6.4p1, 5.5.5p1.

Notes: Reproduces with WebGL, Android and iOS platforms. Disabling "Strip Engine Code" on WebGL does not prevent issue from happening. However, setting stripping level to none when building with Android or iOS prevents this issue from happening. With any other stripping level selected, issue reproduces.