Issue 1:
The real problem is that flutter test command on linux requires libGLU.so.1 but it's lack is neither detected by doctor nor listed as a requirement in documentation.

According to #8493 there should be no dependency on that shared library. So either @Hixie's assumption from #8493 (comment) is wrong or it was just introduced again in the meantime.

Fix consists of installing libglu1-mesa.

Here are the logs:

root@dc2bcbfdb26b:/bitrise/src/flutter-app-example# flutter test
00:05 +0: loading /bitrise/src/flutter-app-example/test/widget_test.dart Shell: /bitrise/src/flutter/bin/cache/artifacts/engine/linux-x64/flutter_tester: error while loading shared libraries: libGLU.so.1: cannot open shared object file: No such file or directory
00:05 +0 -1: loading /bitrise/src/flutter-app-example/test/widget_test.dart [E]
Failed to load "/bitrise/src/flutter-app-example/test/widget_test.dart":
Shell subprocess crashed with unexpected exit code 127 before connecting to test harness.
Test: /bitrise/src/flutter-app-example/test/widget_test.dart
Shell: /bitrise/src/flutter/bin/cache/artifacts/engine/linux-x64/flutter_tester

00:05 +0 -1: Some tests failed.
root@dc2bcbfdb26b:/bitrise/src/flutter-app-example# ldd /bitrise/src/flutter/bin/cache/artifacts/engine/linux-x64/flutter_tester |grep libGLU
libGLU.so.1 => not found

root@dc2bcbfdb26b:/bitrise/src/flutter-app-example# flutter --version
Flutter 0.3.1 • channel beta • https://github.com/flutter/flutter.git
Framework • revision 12bbaba9ae (2 weeks ago) • 2018-04-19 23:36:15 -0700
Engine • revision 09d05a3891
Tools • Dart 2.0.0-dev.48.0.flutter-fe606f890b

Issue 2:
We'd like to build Flutter test runner with GPU support disabled in Skia, by setting the skia_enable_gpu = false GN argument. However, today that results in the following error:

[12253/19539] CXX host_x64/obj/third_party/flutter/shell/gpu/gpu.gpu_surface_gl.o
FAILED: host_x64/obj/third_party/flutter/shell/gpu/gpu.gpu_surface_gl.o
../../buildtools/linux-x64/clang/bin/clang++ -MD -MF host_x64/obj/third_party/flutter/shell/gpu/gpu.gpu_surface_gl.o.d -DSK_HAS_JPEG_LIBRARY -DSK_SUPPORT_PDF -DSK_HAS_PNG_LIBRARY -DSK_USE_SKCMS -DSK_XML -DFLUTTER_RUNTIME_MODE_DEBUG=1 -DFLUTTER_RUNTIME_MODE_PROFILE=2 -DFLUTTER_RUNTIME_MODE_RELEASE=3 -DFLUTTER_RUNTIME_MODE=1 -DWTF_USE_DYNAMIC_ANNOTATIONS=1 -DENABLE_OPENTYPE_VERTICAL=1 -DSK_SAMPLES_FOR_X -DSK_DISABLE_EXPLICIT_GPU_RESOURCE_ALLOCATION -DSK_DISABLE_RENDER_TARGET_SORTING -DSK_SUPPORT_LEGACY_BACKEND_OBJECTS -DSK_DONT_OPTIMIZE_SRC_PROFILES_FOR_SPEED -DSK_DONT_OPTIMIZE_DST_PROFILES_FOR_SPEED -DSK_SUPPORT_GPU=0 -I../.. -Ihost_x64/gen -I../../third_party -I../../garnet/public -I../../peridot/public -I../../topaz/public -Ihost_x64/gen/garnet/public -Ihost_x64/gen/peridot/public -Ihost_x64/gen/topaz/public -I../../topaz -I../../third_party/dart/runtime -I../../third_party/skia/include/android -I../../third_party/skia/include/c -I../../third_party/skia/include/codec -I../../third_party/skia/include/config -I../../third_party/skia/include/core -I../../third_party/skia/include/effects -I../../third_party/skia/include/encode -I../../third_party/skia/include/gpu -I../../third_party/skia/include/gpu/gl -I../../third_party/skia/include/atlastext -I../../third_party/skia/include/pathops -I../../third_party/skia/include/ports -I../../third_party/skia/include/svg -I../../third_party/skia/include/utils -I../../third_party/skia/include/utils/mac -g --sysroot=/usr/local/google/home/phosek/fuchsia/buildtools/linux-x64/sysroot -fdebug-prefix-map=/usr/local/google/home/phosek/fuchsia=../.. -no-canonical-prefixes -Wall -Wextra -Wno-unused-parameter -fvisibility=hidden -g -Og -fvisibility-inlines-hidden -std=c++14 -stdlib=libc++ -fno-exceptions -fno-rtti -c ../../third_party/flutter/shell/gpu/gpu_surface_gl.cc -o host_x64/obj/third_party/flutter/shell/gpu/gpu.gpu_surface_gl.o
../../third_party/flutter/shell/gpu/gpu_surface_gl.cc:115:25: error: no matching constructor for initialization of 'GrBackendRenderTarget'
GrBackendRenderTarget render_target(size.fWidth, // width
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~
../../third_party/skia/include/gpu/GrBackendSurface.h:32:14: note: candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 5 were provided
class SK_API GrBackendRenderTarget {
^
../../third_party/skia/include/gpu/GrBackendSurface.h:32:14: note: candidate constructor (the implicit move constructor) not viable: requires 1 argument, but 5 were provided
../../third_party/skia/include/gpu/GrBackendSurface.h:34:5: note: candidate constructor not viable: requires 0 arguments, but 5 were provided
GrBackendRenderTarget() {}
^
1 error generated.
[12310/19539] ACTION //topaz/shell/userpicker_device_shell:userpicker_device_shell_dart_library_identify_sources(//build/dart:dartlang)
ninja: build stopped: subcommand failed.

This is when building Flutter test running for host as part of Fuchsia.