This same issue is causing https://www.khronos.org/registry/webgl/conformance-suites/1.0.3/conformance/glsl/bugs/sampler-array-using-loop-index.html?webglVersion=1 to fail under Linux. See Bug 1526133
Bug 1526133 Comment 2 Edit History
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This same issue is causing Bug 1399501 to fail.