Code refactoring for end2end tests.

This change:
1) uses the new style ANGLE_SKIP_TEST_IF to skip tests.
2) replaces compile-time definition for OSX to skip tests by run-time
function IsOSX() to skip tests, in order to align with ANGLE_SKIP_TEST_IF.
3) fixes a couple of typos.

BUG=angleproject:2005

Change-Id: I5af77d82257536b9eb79e26afa502f5b91ff6d31
Reviewed-on: https://chromium-review.googlesource.com/915861
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/tests/gl_tests/CopyTextureTest.cpp b/src/tests/gl_tests/CopyTextureTest.cpp
index c8c6d13..153209a 100644
--- a/src/tests/gl_tests/CopyTextureTest.cpp
+++ b/src/tests/gl_tests/CopyTextureTest.cpp
@@ -150,14 +150,9 @@
         return;
     }
 
-    if (getClientMajorVersion() < 3 &&
-        (!extensionEnabled("GL_EXT_texture_storage") || !extensionEnabled("GL_OES_rgb8_rgba8")))
-    {
-        std::cout
-            << "Test skipped due to missing ES3 or GL_EXT_texture_storage or GL_OES_rgb8_rgba8"
-            << std::endl;
-        return;
-    }
+    ANGLE_SKIP_TEST_IF(
+        getClientMajorVersion() < 3 &&
+        (!extensionEnabled("GL_EXT_texture_storage") || !extensionEnabled("GL_OES_rgb8_rgba8")));
 
     GLColor pixels = GLColor::red;
 
@@ -683,18 +678,10 @@
         return;
     }
 
-    if (getClientMajorVersion() < 3 && !extensionEnabled("GL_OES_fbo_render_mipmap"))
-    {
-        std::cout << "Test skipped because ES3 or GL_OES_fbo_render_mipmap is missing."
-                  << std::endl;
-        return;
-    }
+    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3 &&
+                       !extensionEnabled("GL_OES_fbo_render_mipmap"));
 
-    if (IsOSX() && IsIntel())
-    {
-        std::cout << "Test skipped on Mac Intel." << std::endl;
-        return;
-    }
+    ANGLE_SKIP_TEST_IF(IsOSX() && IsIntel());
 
     GLColor pixels[] = {GLColor::red, GLColor::red, GLColor::red, GLColor::red};
 
@@ -1168,11 +1155,7 @@
         return;
     }
 
-    if (!extensionEnabled("GL_EXT_color_buffer_float"))
-    {
-        std::cout << "Test skipped due to missing GL_EXT_color_buffer_float." << std::endl;
-        return;
-    }
+    ANGLE_SKIP_TEST_IF(!extensionEnabled("GL_EXT_color_buffer_float"));
 
     auto testOutput = [this](GLuint texture, const GLColor32F &expectedColor) {
         const std::string vs =