gpu: Forbid aliasing inactive attributes in GLSL 3+

The GLSL 3.00.6 spec forbids aliasing of attributes even if they are
inactive. Earlier versions of GLSL still allow it. This mirrors an ANGLE
change: http://crrev.com/c/1005077

Fixes WebGL conformance test
conformance2/attribs/gl-bindAttribLocation-aliasing-inactive.html

Bug: 829541
Change-Id: I8163c3fac3ca7b5b0c6efd9f9a88b9f92c2d19f6
Reviewed-on: https://chromium-review.googlesource.com/c/1359413Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: James Darpinian <jdarpinian@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613362}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -82,11 +82,6 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
     # All platforms.
     self.Fail('conformance2/glsl3/tricky-loop-conditions.html', bug=905001)
 
-    # All non-ANGLE platforms.
-    self.Fail('conformance2/attribs/' +
-        'gl-bindAttribLocation-aliasing-inactive.html',
-        ['no_angle'], bug=829541)
-
     # Newly introduced flaky failure.
     # TODO(kbr): re-enable after fixing test.
     self.Flaky('conformance/textures/misc/' +

gpu/command_buffer/service/program_manager.cc

@@ -1881,7 +1881,7 @@ bool Program::DetectAttribLocationBindingConflicts() const {
         continue;
       attrib = shader->GetAttribInfo(*mapped_name);
       if (attrib) {
-        if (attrib->staticUse)
+        if (shader->shader_version() >= 300 || attrib->staticUse)
           break;
         else
           attrib = nullptr;