Vulkan: Implement ANGLE_translated_shader_source

BUG=angleproject:2909

Change-Id: Ie59c1206e2ce4940e27fed7887dbee665721049b
Reviewed-on: https://chromium-review.googlesource.com/c/1351354
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>

Author: vonture

src/libANGLE/renderer/vulkan/ShaderVk.cpp

@@ -51,7 +51,7 @@ bool ShaderVk::postTranslateCompile(gl::ShCompilerInstance *compiler, std::strin
 
 std::string ShaderVk::getDebugInfo() const
 {
-    return std::string();
+    return mData.getTranslatedSource();
 }
 
 }  // namespace rx

src/libANGLE/renderer/vulkan/vk_caps_utils.cpp

@@ -48,6 +48,7 @@ void GenerateCaps(const VkPhysicalDeviceProperties &physicalDeviceProperties,
     outExtensions->debugMarker     = true;
     outExtensions->robustness      = true;
     outExtensions->textureBorderClamp = false;  // not implemented yet
+    outExtensions->translatedShaderSource = true;
 
     // We use secondary command buffers almost everywhere and they require a feature to be
     // able to execute in the presence of queries.  As a result, we won't support queries