Implement case mapping using the Unicode default case mapping algorithm.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 240f3eddc5b5ab0dfaff519cf0a3577b67e23b7f..1ea941b164997d64f5f4d99a3ba8309f4e8e11e7 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -2364,6 +2364,15 @@ class String : public Instance {
                               intptr_t length,
                               Heap::Space space = Heap::kNew);
 
+  static RawString* Transform(int32_t (*mapping)(int32_t ch),
+                              const String& str,
+                              Heap::Space space = Heap::kNew);
+
+  static RawString* ToUpperCase(const String& str,
+                                Heap::Space space = Heap::kNew);
+  static RawString* ToLowerCase(const String& str,
+                                Heap::Space space = Heap::kNew);
+
   static RawString* NewSymbol(const char* str);
   template<typename T>
   static RawString* NewSymbol(const T* characters, intptr_t len);
@@ -2435,6 +2444,10 @@ class OneByteString : public String {
                                      intptr_t length,
                                      Heap::Space space);
 
+  static RawOneByteString* Transform(int32_t (*mapping)(int32_t ch),
+                                     const String& str,
+                                     Heap::Space space);
+
  private:
   uint8_t* CharAddr(intptr_t index) const {
     // TODO(iposva): Determine if we should throw an exception here.
@@ -2486,6 +2499,10 @@ class TwoByteString : public String {
                                      intptr_t length,
                                      Heap::Space space);
 
+  static RawTwoByteString* Transform(int32_t (*mapping)(int32_t ch),
+                                     const String& str,
+                                     Heap::Space space);
+
  private:
   uint16_t* CharAddr(intptr_t index) const {
     ASSERT((index >= 0) && (index < Length()));
@@ -2533,6 +2550,10 @@ class FourByteString : public String {
                                       intptr_t length,
                                       Heap::Space space);
 
+  static RawFourByteString* Transform(int32_t (*mapping)(int32_t ch),
+                                      const String& str,
+                                      Heap::Space space);
+
  private:
   uint32_t* CharAddr(intptr_t index) const {
     ASSERT((index >= 0) && (index < Length()));