Reland "Replace gl::trace logging with Chromium style logging"

Removing one usage of FormatString() and its static buffer.
And preparation for Platform logging.

Fix incorrect enabling of ERR() calls in UNIMPLEMENTED() and
UNREACHABLE(), resulting in increased code size and
<iostream> adding 5 static initializers to chrome because of
cerr referenced in statically linked translator.

BUG=angleproject:1660

Change-Id: I7caa18036118d532e0544f75278602559172ae04
Reviewed-on: https://chromium-review.googlesource.com/431457
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/validationES2.cpp b/src/libANGLE/validationES2.cpp
index dc2a008..13fcfe6 100644
--- a/src/libANGLE/validationES2.cpp
+++ b/src/libANGLE/validationES2.cpp
@@ -1910,8 +1910,8 @@
                                   dstX0, dstY0, dstX1, dstY1))
                 {
                     // only whole-buffer copies are permitted
-                    ERR("Only whole-buffer depth and stencil blits are supported by this "
-                        "implementation.");
+                    ERR() << "Only whole-buffer depth and stencil blits are supported by this "
+                             "implementation.";
                     context->handleError(Error(GL_INVALID_OPERATION));
                     return false;
                 }
@@ -3839,9 +3839,9 @@
 
         if (constantColorUsed && constantAlphaUsed)
         {
-            ERR("Simultaneous use of GL_CONSTANT_ALPHA/GL_ONE_MINUS_CONSTANT_ALPHA and "
-                "GL_CONSTANT_COLOR/GL_ONE_MINUS_CONSTANT_COLOR not supported by this "
-                "implementation.");
+            ERR() << "Simultaneous use of GL_CONSTANT_ALPHA/GL_ONE_MINUS_CONSTANT_ALPHA and "
+                     "GL_CONSTANT_COLOR/GL_ONE_MINUS_CONSTANT_COLOR not supported by this "
+                     "implementation.";
             context->handleError(Error(GL_INVALID_OPERATION,
                                        "Simultaneous use of "
                                        "GL_CONSTANT_ALPHA/GL_ONE_MINUS_CONSTANT_ALPHA and "