First attempt to capture parser/translation errors in browser.

src/IceGlobalContext.h

Index: src/IceGlobalContext.h
diff --git a/src/IceGlobalContext.h b/src/IceGlobalContext.h
index 9264d4302fbc0d6990e4261c399630ea1fafab39..8154e002c4e5aedaba25296bdde7860d8a94e8f8 100644
--- a/src/IceGlobalContext.h
+++ b/src/IceGlobalContext.h
@@ -145,14 +145,19 @@ class GlobalContext {
   };
 
 public:
+  // The dump stream is a log stream while emit is the stream code
+  // is emitted to. The error stream is strictly for logging errors.
+  // If an error stream is not provided, the dump stream will be
+  // used instead.
   GlobalContext(Ostream *OsDump, Ostream *OsEmit, ELFStreamer *ELFStreamer,
-                const ClFlags &Flags);
+                const ClFlags &Flags, Ostream *OsError = nullptr);
   ~GlobalContext();
 
-  // The dump and emit streams need to be used by only one thread at a
-  // time.  This is done by exclusively reserving the streams via
-  // lockStr() and unlockStr().  The OstreamLocker class can be used
-  // to conveniently manage this.
+  //
+  // The dump, error, and emit streams need to be used by only one
+  // thread at a time.  This is done by exclusively reserving the
+  // streams via lockStr() and unlockStr().  The OstreamLocker class
+  // can be used to conveniently manage this.
   //
   // The model is that a thread grabs the stream lock, then does an
   // arbitrary amount of work during which far-away callees may grab
@@ -163,6 +168,7 @@ public:
   void lockStr() { StrLock.lock(); }
   void unlockStr() { StrLock.unlock(); }
   Ostream &getStrDump() { return *StrDump; }
+  Ostream &getStrError() { return StrError ? *StrError : *StrDump; }
   Ostream &getStrEmit() { return *StrEmit; }
 
   LockedPtr<ErrorCode> getErrorStatus() {
@@ -418,6 +424,7 @@ private:
   StrLockType StrLock;
   Ostream *StrDump; // Stream for dumping / diagnostics
   Ostream *StrEmit; // Stream for code emission
+  Ostream *StrError; // If non-null, stream for logging errors.
 
   ICE_CACHELINE_BOUNDARY;