Init Blend State color mask defaults.

This is an unrelated code cleanup. Previously we would only init these
member variables in the gl::State initialization code.

Bug: angleproject:3611
Change-Id: I3aa34958ce5b00542d45ef63e0b32010b2eb3220
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1902188
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>

src/libANGLE/State.cpp

@@ -355,11 +355,6 @@ void State::initialize(Context *context)
     mNearZ           = 0.0f;
     mFarZ            = 1.0f;
 
-    mBlend.colorMaskRed   = true;
-    mBlend.colorMaskGreen = true;
-    mBlend.colorMaskBlue  = true;
-    mBlend.colorMaskAlpha = true;
-
     mActiveSampler = 0;
 
     mVertexAttribCurrentValues.resize(caps.maxVertexAttributes);

src/libANGLE/angletypes.cpp

@@ -52,6 +52,10 @@ BlendState::BlendState()
     blendEquationAlpha    = GL_FUNC_ADD;
     sampleAlphaToCoverage = false;
     dither                = true;
+    colorMaskRed          = true;
+    colorMaskGreen        = true;
+    colorMaskBlue         = true;
+    colorMaskAlpha        = true;
 }
 
 BlendState::BlendState(const BlendState &other)