a === b -> identical(a, b)

sdk/lib/core/string_buffer.dart

Index: sdk/lib/core/string_buffer.dart
diff --git a/sdk/lib/core/string_buffer.dart b/sdk/lib/core/string_buffer.dart
index 0561d83c217eaca346d937d0aab0d5aa038d3a44..0b91e96332d1dedf4f4c30cac0138335ebe01cc5 100644
--- a/sdk/lib/core/string_buffer.dart
+++ b/sdk/lib/core/string_buffer.dart
@@ -68,7 +68,7 @@ class _StringBufferImpl implements StringBuffer {
   }
 
   bool get isEmpty {
-    return _length === 0;
+    return _length == 0;
   }
 
   /**
@@ -76,7 +76,7 @@ class _StringBufferImpl implements StringBuffer {
    */
   StringBuffer add(Object obj) {
     String str = obj.toString();
-    if (str === null || str.isEmpty) {
+    if (str == null || str.isEmpty) {
       return this;
     }
     _buffer.add(str);
@@ -115,8 +115,8 @@ class _StringBufferImpl implements StringBuffer {
    * Returns the contents of buffer as a concatenated string.
    */
   String toString() {
-    if (_buffer.length === 0) return "";
-    if (_buffer.length === 1) return _buffer[0];
+    if (_buffer.length == 0) return "";
+    if (_buffer.length == 1) return _buffer[0];
     String result = _StringImpl.concatAll(_buffer);
     _buffer.clear();
     _buffer.add(result);