Revert "Child fragment processors are now written as separate functions"

This reverts commit 0364bde2c49616bc9d2f68742d36bfedbeb7e950.

Reason for revert: bot breakage, e.g. https://chromium-swarm.appspot.com/task?id=44942724fab4b710 and https://chromium-swarm.appspot.com/task?id=44938767e5fbb810
Original change's description:
> Child fragment processors are now written as separate functions
> instead of inline
> 
> Bug: skia:
> Change-Id: I3c6c876fea9cfcc311fc09c0fdf0375b776004aa
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/210632
> Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>

TBR=ethannicholas@google.com,michaelludwig@google.com

Change-Id: If33c1f554a090cd7541878e77712d5ce968ec70a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/211943
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/gpu/effects/GrSkSLFP.cpp b/src/gpu/effects/GrSkSLFP.cpp
index cece9c1..f8fe85d 100644
--- a/src/gpu/effects/GrSkSLFP.cpp
+++ b/src/gpu/effects/GrSkSLFP.cpp
@@ -159,14 +159,12 @@
                                                                    SkSL::String(v->fName).c_str()));
             }
         }
-        GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
         std::vector<SkString> childNames;
         for (int i = 0; i < this->numChildProcessors(); ++i) {
-            SkString name = SkStringPrintf("_child%d", i);
-            fragBuilder->codeAppendf("half4 %s;\n", name.c_str());
-            childNames.push_back(std::move(name));
-            this->invokeChild(i, childNames[i].c_str(), args);
+            childNames.push_back(SkStringPrintf("_child%d", i));
+            this->emitChild(i, &childNames[i], args);
         }
+        GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
         int substringStartIndex = 0;
         int formatArgIndex = 0;
         for (size_t i = 0; i < fGLSL.length(); ++i) {