Add a GL cap for instanced rendering to floating point

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 9dd0fbe36edd37b9d80108cf35cc24356a3b6611..431390697b2eea8e8a7796a947f771a478b24a82 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -40,6 +40,7 @@ GrGLCaps::GrGLCaps(const GrContextOptions& contextOptions,
     fDrawIndirectSupport = false;
     fMultiDrawIndirectSupport = false;
     fBaseInstanceSupport = false;
+    fCanDrawIndirectToFloat = false;
     fUseNonVBOVertexAndIndexDynamicData = false;
     fIsCoreProfile = false;
     fBindFragDataLocationSupport = false;
@@ -530,6 +531,14 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
         fBaseInstanceSupport = ctxInfo.hasExtension("GL_EXT_base_instance");
     }
 
+    // OS X doesn't seem to write correctly to floating point textures when using glDraw*Indirect,
+    // regardless of the underlying GPU.
+#ifndef SK_BUILD_FOR_MAC
+    if (fDrawIndirectSupport) {
+        fCanDrawIndirectToFloat = true;
+    }
+#endif
+
     this->initShaderPrecisionTable(ctxInfo, gli, glslCaps);
 
     if (contextOptions.fUseShaderSwizzling) {
@@ -1112,6 +1121,7 @@ SkString GrGLCaps::dump() const {
     r.appendf("Draw indirect support: %s\n", (fDrawIndirectSupport ? "YES" : "NO"));
     r.appendf("Multi draw indirect support: %s\n", (fMultiDrawIndirectSupport ? "YES" : "NO"));
     r.appendf("Base instance support: %s\n", (fBaseInstanceSupport ? "YES" : "NO"));
+    r.appendf("Can draw indirect to float: %s\n", (fCanDrawIndirectToFloat ? "YES" : "NO"));
     r.appendf("Use non-VBO for dynamic data: %s\n",
              (fUseNonVBOVertexAndIndexDynamicData ? "YES" : "NO"));
     r.appendf("RGBA 8888 pixel ops are slow: %s\n", (fRGBA8888PixelsOpsAreSlow ? "YES" : "NO"));