Rearrange emit vs emitIAS. Wait till function is done before dumping text.

Eventually, I wanted to have a flag "UseELFWriter" like:
https://codereview.chromium.org/678533005/diff/120001/src/IceCfg.cpp

Where the emit OStream would not have text, and only have
binary. This refactor hopefully means fewer places to
check for a flag to disable the text version of IAS,
and be able to write binary. Otherwise, there are some
text labels for branches that are still being dumped out.

BUG=none
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/700263003
diff --git a/src/IceCfg.h b/src/IceCfg.h
index fb8ebd9..2a1e602 100644
--- a/src/IceCfg.h
+++ b/src/IceCfg.h
@@ -94,9 +94,6 @@
   template <typename T> T *getAssembler() const {
     return static_cast<T *>(TargetAssembler.get());
   }
-  bool useIntegratedAssembler() const {
-    return getContext()->getFlags().UseIntegratedAssembler;
-  }
   bool hasComputedFrame() const;
   bool getFocusedTiming() const { return FocusedTiming; }
   void setFocusedTiming() { FocusedTiming = true; }
@@ -131,6 +128,8 @@
   const CfgNode *getCurrentNode() const { return CurrentNode; }
 
   void emit();
+  void emitIAS();
+  void emitTextHeader(const IceString &MangledName);
   void dump(const IceString &Message = "");
 
   // Allocate data of type T using the per-Cfg allocator.