Revert "Switched highp float to highfloat and mediump float to half."

This reverts commit 88d99c63878c2d3d340120f0321676f72afcb4f0.

Reason for revert: Believed to be causing unit test failures in Chrome roll:

https://build.chromium.org/p/tryserver.chromium.android/builders/linux_android_rel_ng/builds/364433
https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Ftryserver.chromium.android%2Flinux_android_rel_ng%2F364433%2F%2B%2Frecipes%2Fsteps%2Fcontent_browsertests__with_patch__on_Android%2F0%2Flogs%2FWebRtcCaptureFromElementBrowserTest.VerifyCanvasWebGLCaptureColor%2F0

Original change's description:
> Switched highp float to highfloat and mediump float to half.
> 
> The ultimate goal is to end up with "float" and "half", but this
> intermediate step uses "highfloat" so that it is clear if I missed a
> "float" somewhere. Once this lands, a subsequent CL will switch all
> "highfloats" back to "floats".
> 
> Bug: skia:
> Change-Id: Ia13225c7a0a0a2901e07665891c473d2500ddcca
> Reviewed-on: https://skia-review.googlesource.com/31000
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>

TBR=bsalomon@google.com,csmartdalton@google.com,ethannicholas@google.com

Change-Id: I8bfa97547ac3920d433665f161d27df3f15c83aa
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/35705
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp b/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp
index 0cb7e4d..d9d17e5 100644
--- a/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp
+++ b/src/gpu/glsl/GrGLSLPrimitiveProcessor.cpp
@@ -43,12 +43,13 @@
     SkASSERT(colorUniform);
     const char* stagedLocalVarName;
     *colorUniform = uniformHandler->addUniform(kFragment_GrShaderFlag,
-                                               kHalf4_GrSLType,
+                                               kVec4f_GrSLType,
+                                               kDefault_GrSLPrecision,
                                                "Color",
                                                &stagedLocalVarName);
     fragBuilder->codeAppendf("%s = %s;", outputName, stagedLocalVarName);
     if (fragBuilder->getProgramBuilder()->shaderCaps()->mustObfuscateUniformColor()) {
-        fragBuilder->codeAppendf("%s = max(%s, half4(0, 0, 0, 0));", outputName, outputName);
+        fragBuilder->codeAppendf("%s = max(%s, float4(0, 0, 0, 0));", outputName, outputName);
     }
 }