Reproduction steps:
1. Open the attached project named "Case_1141821"
2. Open the "TestShader"
3. Observe the console window

Expected result: No errors are thrown and the shader is functional
Actual result: Compilation error is thrown and the shader is broken

Reproducible with: 2017.4.25f1, 2018.3.13f1, 2019.1.0f2, 2019.2.0a11

Notes:
1. The bug is fixed in ShaderGraph version 5.3.1 or newer
2. Tested with package versions 3.0.0, 3.3.0, 4.0.0, 5.0.0, 5.2.3, 5.3.1, 5.10.0

Full error message:
Compilation error in graph at line 5 (on ):
Parse error: syntax error, unexpected ',', expecting ')'
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)