[turbofan] Make value projection collection more robust.

This makes the collection logic of {Projection} nodes (i.e. value
projections for multi-value returning calls) more robust. The projection
nodes by now have a control input, which in turn can make them appear
more than once in the use list of a call. We should limit the use list
inspection to value edges only. This is in preparation of eliding any
redundant {IfSuccess} control node.

R=jarin@chromium.org

Change-Id: I9bb4cc0e2e877976be55a894af972aa83d07d7d7
Reviewed-on: https://chromium-review.googlesource.com/450244Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43608}

src/compiler/instruction-selector.cc

@@ -681,12 +681,13 @@ void InstructionSelector::InitializeCallBuffer(Node* call, CallBuffer* buffer,
       buffer->output_nodes.push_back(call);
     } else {
       buffer->output_nodes.resize(buffer->descriptor->ReturnCount(), nullptr);
-      for (auto use : call->uses()) {
-        if (use->opcode() != IrOpcode::kProjection) continue;
-        size_t const index = ProjectionIndexOf(use->op());
+      for (Edge const edge : call->use_edges()) {
+        if (!NodeProperties::IsValueEdge(edge)) continue;
+        DCHECK(edge.from()->opcode() == IrOpcode::kProjection);
+        size_t const index = ProjectionIndexOf(edge.from()->op());
         DCHECK_LT(index, buffer->output_nodes.size());
         DCHECK(!buffer->output_nodes[index]);
-        buffer->output_nodes[index] = use;
+        buffer->output_nodes[index] = edge.from();
       }
     }