Remove predefined precision qualifiers from ESSL3 samplers

New sampler types in ESSL3 should not have default precision qualifiers.
This is specified in ESSL 3.00.4 section 4.5.4.

BUG=angleproject:1222
TEST=angle_unittests

Change-Id: I9c8e7a5fbb4278db80de79bcaeebaf23e64242a0
Reviewed-on: https://chromium-review.googlesource.com/312048
Tryjob-Request: Olli Etuaho <oetuaho@nvidia.com>
Tested-by: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Zhenyao Mo <zmo@chromium.org>
diff --git a/src/tests/gl_tests/TextureTest.cpp b/src/tests/gl_tests/TextureTest.cpp
index c744529..54a7c03 100644
--- a/src/tests/gl_tests/TextureTest.cpp
+++ b/src/tests/gl_tests/TextureTest.cpp
@@ -278,7 +278,7 @@
         const std::string fragmentShaderSource2DArray =
             "#version 300 es\n"
             "precision highp float;\n"
-            "uniform sampler2DArray tex2DArray;\n"
+            "uniform highp sampler2DArray tex2DArray;\n"
             "in vec2 texcoord;\n"
             "out vec4 fragColor;\n"
             "void main()\n"