Inline Math.sqrt in new compilers.

runtime/vm/flow_graph_compiler_x64.h

Index: runtime/vm/flow_graph_compiler_x64.h
===================================================================
--- runtime/vm/flow_graph_compiler_x64.h	(revision 8700)
+++ runtime/vm/flow_graph_compiler_x64.h	(working copy)
@@ -113,6 +113,8 @@
                           intptr_t argument_count,
                           const Array& argument_names);
 
+  virtual void GenerateInlinedMathSqrt(Label* done);
+
   void GenerateNumberTypeCheck(Register kClassIdReg,
                                const AbstractType& type,
                                Label* is_instance_lbl,
@@ -169,6 +171,7 @@
 
   const Bool& bool_true() const { return bool_true_; }
   const Bool& bool_false() const { return bool_false_; }
+  const Class& double_class() const { return double_class_; }
 
   static const int kLocalsOffsetFromFP = (-1 * kWordSize);
 
@@ -271,6 +274,7 @@
 
   const Bool& bool_true_;
   const Bool& bool_false_;
+  const Class& double_class_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphCompiler);
 };