VM: Avoid allocating strings when disassembling code.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index fbc72e2c24a5a105d437f65e793012dc5d5298a4..a7b42bb3cd2b9ea37e01bb655e0a1c291f47cb69 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -4928,8 +4928,8 @@ class Code : public Object {
   uword GetPcForDeoptId(intptr_t deopt_id, RawPcDescriptors::Kind kind) const;
   intptr_t GetDeoptIdForOsr(uword pc) const;
 
-  RawString* Name() const;
-  RawString* QualifiedName() const;
+  const char* Name() const;
+  const char* QualifiedName() const;
 
   int64_t compile_timestamp() const {
 #if defined(DART_PRECOMPILED_RUNTIME)
@@ -5806,10 +5806,6 @@ class AbstractType : public Instance {
     return BuildName(kUserVisibleName);
   }
 
-  // Same as user visible name, but including the URI of each occuring type.
-  // Used to report errors involving types with identical names.
-  virtual RawString* UserVisibleNameWithURI() const;
-
   // Returns a formatted list of occuring types with their URI.
   virtual RawString* EnumerateURIs() const;
 
@@ -6965,7 +6961,7 @@ class String : public Instance {
   static RawString* EscapeSpecialCharacters(const String& str);
   // Encodes 'str' for use in an Internationalized Resource Identifier (IRI),
   // a generalization of URI (percent-encoding). See RFC 3987.
-  static RawString* EncodeIRI(const String& str);
+  static const char* EncodeIRI(const String& str);
   // Returns null if 'str' is not a valid encoding.
   static RawString* DecodeIRI(const String& str);
   static RawString* Concat(const String& str1,