Revert "Use nullptr consistently in TIntermConstantUnion::fold"
Revert "Use nullptr consistently in TIntermConstantUnion::fold"

Part of a chain causing compile errors on Mac. Example:

../../third_party/angle/src/compiler/translator/IntermNode.cpp:1216:89: error: no member named 'sin' in namespace 'std'; did you mean 'sinf'?

http://build.chromium.org/p/chromium.gpu.fyi/builders/GPU%20Linux%20Builder/builds/33747

This reverts commit 72ed20d4bb5a5c55d9909d6cc9b7a0e89e4a81a2.

Change-Id: Ia6119f6081b3184deef3deef25b9e3f43ff2e2a6
Reviewed-on: https://chromium-review.googlesource.com/265586
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Tested-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>

mrobinson/rust-angle,mikolalysenko/angle,vvuk/angle,mlfarrell/angle,ecoal95/angle,ppy/angle,ppy/angle,mikolalysenko/angle,ppy/angle,larsbergstrom/angle,mybios/angle,domokit/waterfall,csa7mdm/angle,vvuk/angle,bsergean/angle,bsergean/angle,csa7mdm/angle,mrobinson/rust-angle,csa7mdm/angle,mlfarrell/angle,mybios/angle,ppy/angle,crezefire/angle,MSOpenTech/angle,mrobinson/rust-angle,mikolalysenko/angle,larsbergstrom/angle,ecoal95/angle,mlfarrell/angle,vvuk/angle,vvuk/angle,bsergean/angle,ghostoy/angle,domokit/waterfall,ecoal95/angle,ghostoy/angle,mrobinson/rust-angle,mlfarrell/angle,crezefire/angle,ghostoy/angle,MSOpenTech/angle,mikolalysenko/angle,MSOpenTech/angle,bsergean/angle,ecoal95/angle,ecoal95/angle,MSOpenTech/angle,larsbergstrom/angle,csa7mdm/angle,mrobinson/rust-angle,mybios/angle,ghostoy/angle,crezefire/angle,crezefire/angle,mybios/angle,larsbergstrom/angle