Fix unit tests when workarounds are enabled

Change-Id: Ia660a6d91aa3615e0fa21fba67f5029c131b1ba2
Reviewed-on: https://skia-review.googlesource.com/128983
Commit-Queue: Adrienne Walker <enne@chromium.org>
Reviewed-by: Brian Salomon <bsalomon@google.com>

src/gpu/gl/GrGLCaps.cpp

@@ -2815,7 +2815,11 @@ int GrGLCaps::maxRenderTargetSampleCount(GrPixelConfig config) const {
     if (!table.count()) {
         return 0;
     }
-    return table[table.count() - 1];
+    int count = table[table.count() - 1];
+    if (fDriverBugWorkarounds.max_msaa_sample_count_4) {
+        count = SkTMin(count, 4);
+    }
+    return count;
 }
 
 bool validate_sized_format(GrGLenum format, SkColorType ct, GrPixelConfig* config,

src/gpu/gl/GrGLCreateNullInterface.cpp

@@ -403,6 +403,9 @@ public:
         Framebuffer* framebuffer = fFramebufferManager.lookUp(id);
 
         GrAlwaysAssert(GR_GL_RENDERBUFFER == renderbuffertarget);
+        if (!renderBufferID && !fCurrRenderbuffer) {
+           return;
+        }
         GrAlwaysAssert(fCurrRenderbuffer);
         Renderbuffer* renderbuffer = fRenderbufferManager.lookUp(fCurrRenderbuffer);
 

src/gpu/gl/GrGLGpu.cpp

@@ -3399,7 +3399,9 @@ void GrGLGpu::bindFramebuffer(GrGLenum target, GrGLuint fboid) {
     }
 
     // The driver forgets the correct scissor when modifying the FBO binding.
-    fHWScissorSettings.fRect.pushToGLScissor(this->glInterface());
+    if (!fHWScissorSettings.fRect.isInvalid()) {
+        fHWScissorSettings.fRect.pushToGLScissor(this->glInterface());
+    }
 
     // crbug.com/222018 - Also on QualComm, the flush here avoids flicker,
     // it's unclear how this bug works.

src/gpu/gl/GrGLIRect.h

@@ -85,6 +85,8 @@ struct GrGLIRect {
     }
 
     void invalidate() {fLeft = fWidth = fBottom = fHeight = -1;}
+    bool isInvalid() const { return fLeft == -1 && fWidth == -1 && fBottom == -1
+        && fHeight == -1; }
 
     bool operator ==(const GrGLIRect& glRect) const {
         return 0 == memcmp(this, &glRect, sizeof(GrGLIRect));