Refactor emitting of deoptimization descriptors for calls.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
===================================================================
--- runtime/vm/intermediate_language.h	(revision 40101)
+++ runtime/vm/intermediate_language.h	(working copy)
@@ -2498,6 +2498,12 @@
 
   virtual bool CanDeoptimize() const { return true; }
 
+  virtual bool CanBecomeDeoptimizationTarget() const {
+    // AssertAssignable instructions that are specialized by the optimizer
+    // (e.g. replaced with CheckClass) need a deoptimization descriptor before.
+    return true;
+  }
+
   virtual Definition* Canonicalize(FlowGraph* flow_graph);
 
   virtual bool AllowsCSE() const { return true; }
@@ -2665,6 +2671,12 @@
 
   virtual bool CanDeoptimize() const { return true; }
 
+  virtual bool CanBecomeDeoptimizationTarget() const {
+    // Instance calls that are specialized by the optimizer need a
+    // deoptimization descriptor before the call.
+    return true;
+  }
+
   virtual EffectSet Effects() const { return EffectSet::All(); }
 
   virtual bool MayThrow() const { return true; }
@@ -3137,6 +3149,12 @@
 
   virtual bool CanDeoptimize() const { return true; }
 
+  virtual bool CanBecomeDeoptimizationTarget() const {
+    // Static calls that are specialized by the optimizer (e.g. sqrt) need a
+    // deoptimization descriptor before the call.
+    return true;
+  }
+
   virtual EffectSet Effects() const { return EffectSet::All(); }
 
   void set_result_cid(intptr_t value) { result_cid_ = value; }