implement opassign, fix bugs in pre/postfix, introduce a let* helper

lib/runtime/dart/convert.js

 var convert;
 (function(exports) {
   'use strict';
   let ASCII = new AsciiCodec();
   let _ASCII_MASK = 127;
   let _allowInvalid = Symbol('_allowInvalid');
   let _nameToEncoding = Symbol('_nameToEncoding');
   let Codec$ = dart.generic(function(S, T) {
     class Codec extends core.Object {
       Codec() {
@@ skipping 12 matching lines @@
       }
     }
     return Codec;
   });
   let Codec = Codec$();
   class Encoding extends Codec$(core.String, core.List$(core.int)) {
     Encoding() {
       super.Codec();
     }
     decodeStream(byteStream) {
-      return dart.as(byteStream.transform(dart.as(this.decoder, async.StreamTransformer$(core.List$(core.int), dynamic))).fold(new core.StringBuffer(), (buffer, string) => dart.dinvoke(buffer, 'write', string), buffer).then((buffer) => dart.dinvoke(buffer, 'toString')), async.Future$(core.String));
+      return dart.as(byteStream.transform(dart.as(this.decoder, async.StreamTransformer$(core.List$(core.int), dynamic))).fold(new core.StringBuffer(), (buffer, string) => (dart.dinvoke(buffer, 'write', string), buffer)).then((buffer) => dart.dinvoke(buffer, 'toString')), async.Future$(core.String));
     }
     static getByName(name) {
       if (name == null)
         return null;
       name = name.toLowerCase();
       return Encoding[_nameToEncoding].get(name);
     }
   }
   dart.defineLazyProperties(Encoding, {
     get _nameToEncoding() {
@@ skipping 302 matching lines @@
     add(chunk) {
       let freeCount = dart.notNull(this[_buffer][core.$length]) - dart.notNull(this[_bufferIndex]);
       if (dart.notNull(chunk[core.$length]) > dart.notNull(freeCount)) {
         let oldLength = this[_buffer][core.$length];
         let newLength = dart.notNull(_ByteCallbackSink[_roundToPowerOf2](dart.notNull(chunk[core.$length]) + dart.notNull(oldLength))) * 2;
         let grown = new typed_data.Uint8List(newLength);
         grown[core.$setRange](0, this[_buffer][core.$length], this[_buffer]);
         this[_buffer] = grown;
       }
       this[_buffer][core.$setRange](this[_bufferIndex], dart.notNull(this[_bufferIndex]) + dart.notNull(chunk[core.$length]), chunk);
-      this[_bufferIndex] = chunk[core.$length];
+      this[_bufferIndex] = dart.notNull(this[_bufferIndex]) + dart.notNull(chunk[core.$length]);
     }
     static [_roundToPowerOf2](v) {
       dart.assert(dart.notNull(v) > 0);
       v = dart.notNull(v) - 1;
-      v = dart.notNull(v) >> 1;
-      v = dart.notNull(v) >> 2;
-      v = dart.notNull(v) >> 4;
-      v = dart.notNull(v) >> 8;
-      v = dart.notNull(v) >> 16;
+      v = dart.notNull(v) | dart.notNull(v) >> 1;
+      v = dart.notNull(v) | dart.notNull(v) >> 2;
+      v = dart.notNull(v) | dart.notNull(v) >> 4;
+      v = dart.notNull(v) | dart.notNull(v) >> 8;
+      v = dart.notNull(v) | dart.notNull(v) >> 16;
       v = dart.notNull(v) + 1;
       return v;
     }
     close() {
       this[_callback](this[_buffer][core.$sublist](0, this[_bufferIndex]));
     }
   }
   _ByteCallbackSink._INITIAL_BUFFER_SIZE = 1024;
   let _ChunkedConversionCallback$ = dart.generic(function(T) {
     class _ChunkedConversionCallback extends core.Function {}
@@ skipping 372 matching lines @@
           let length = dart.notNull(end) - dart.notNull(start);
           chunk = new typed_data.Uint8List.view(chunk.buffer, dart.notNull(chunk.offsetInBytes) + dart.notNull(start), length);
         }
         bytes[core.$add](chunk);
       }
       _JsonUtf8Stringifier.stringify(object, this[_indent], dart.as(this[_toEncodable$], dart.throw_("Unimplemented type (Object) → dynamic")), this[_bufferSize], addChunk);
       if (bytes[core.$length] == 1)
         return bytes[core.$get](0);
       let length = 0;
       for (let i = 0; dart.notNull(i) < dart.notNull(bytes[core.$length]); i = dart.notNull(i) + 1) {
-        length = bytes[core.$get](i)[core.$length];
+        length = dart.notNull(length) + dart.notNull(bytes[core.$get](i)[core.$length]);
       }
       let result = new typed_data.Uint8List(length);
       for (let i = 0, offset = 0; dart.notNull(i) < dart.notNull(bytes[core.$length]); i = dart.notNull(i) + 1) {
         let byteList = bytes[core.$get](i);
         let end = dart.notNull(offset) + dart.notNull(byteList[core.$length]);
         result[core.$setRange](offset, end, byteList);
         offset = end;
       }
       return result;
     }
@@ skipping 450 matching lines @@
       this.writeByte(128 | dart.notNull(charCode) >> 6 & 63);
       this.writeByte(128 | dart.notNull(charCode) & 63);
     }
     writeByte(byte) {
       dart.assert(dart.notNull(byte) <= 255);
       if (this.index == this.buffer[core.$length]) {
         dart.dinvokef(this.addChunk, this.buffer, 0, this.index);
         this.buffer = new typed_data.Uint8List(this.bufferSize);
         this.index = 0;
       }
-      this.buffer[core.$set](((x$) => this.index = dart.notNull(x$) + 1, x$).bind(this)(this.index), byte);
+      this.buffer[core.$set](((x$) => (x$ = this.index, this.index = dart.notNull(x$) + 1, x$)).bind(this)(), byte);
     }
   }
   class _JsonUtf8StringifierPretty extends dart.mixin(_JsonUtf8Stringifier, _JsonPrettyPrintMixin) {
     _JsonUtf8StringifierPretty(toEncodableFunction, indent, bufferSize, addChunk) {
       this.indent = indent;
       super._JsonUtf8Stringifier(toEncodableFunction, dart.as(bufferSize, core.int), dart.as(addChunk, core.Function));
     }
     writeIndentation(count) {
       let indent = this.indent;
       let indentLength = indent[core.$length];
       if (indentLength == 1) {
         let char = indent[core.$get](0);
         while (dart.notNull(count) > 0) {
           this.writeByte(char);
-          count = 1;
+          count = dart.notNull(count) - 1;
         }
         return;
       }
       while (dart.notNull(count) > 0) {
         count = dart.notNull(count) - 1;
         let end = dart.notNull(this.index) + dart.notNull(indentLength);
         if (dart.notNull(end) <= dart.notNull(this.buffer[core.$length])) {
           this.buffer[core.$setRange](this.index, end, indent);
           this.index = end;
         } else {
@@ skipping 493 matching lines @@
       this[_bufferIndex] = 0;
     }
     static [_createBuffer](size) {
       return new typed_data.Uint8List(size);
     }
     [_writeSurrogate](leadingSurrogate, nextCodeUnit) {
       if (_isTailSurrogate(nextCodeUnit)) {
         let rune = _combineSurrogatePair(leadingSurrogate, nextCodeUnit);
         dart.assert(dart.notNull(rune) > dart.notNull(_THREE_BYTE_LIMIT));
         dart.assert(dart.notNull(rune) <= dart.notNull(_FOUR_BYTE_LIMIT));
-        this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 240 | dart.notNull(rune) >> 18);
-        this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 12 & 63);
-        this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 6 & 63);
-        this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
+        this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 240 | dart.notNull(rune) >> 18);
+        this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(rune) >> 12 & 63);
+        this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(rune) >> 6 & 63);
+        this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(rune) & 63);
         return true;
       } else {
-        this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 224 | dart.notNull(leadingSurrogate) >> 12);
-        this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(leadingSurrogate) >> 6 & 63);
-        this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(leadingSurrogate) & 63);
+        this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 224 | dart.notNull(leadingSurrogate) >> 12);
+        this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(leadingSurrogate) >> 6 & 63);
+        this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(leadingSurrogate) & 63);
         return false;
       }
     }
     [_fillBuffer](str, start, end) {
       if (start != end && dart.notNull(_isLeadSurrogate(str.codeUnitAt(dart.notNull(end) - 1)))) {
         end = dart.notNull(end) - 1;
       }
       let stringIndex = null;
       for (stringIndex = start; dart.notNull(stringIndex) < dart.notNull(end); stringIndex = dart.notNull(stringIndex) + 1) {
         let codeUnit = str.codeUnitAt(stringIndex);
         if (dart.notNull(codeUnit) <= dart.notNull(_ONE_BYTE_LIMIT)) {
           if (dart.notNull(this[_bufferIndex]) >= dart.notNull(this[_buffer][core.$length]))
             break;
-          this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), codeUnit);
+          this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), codeUnit);
         } else if (_isLeadSurrogate(codeUnit)) {
           if (dart.notNull(this[_bufferIndex]) + 3 >= dart.notNull(this[_buffer][core.$length]))
             break;
           let nextCodeUnit = str.codeUnitAt(dart.notNull(stringIndex) + 1);
           let wasCombined = this[_writeSurrogate](codeUnit, nextCodeUnit);
-          if (wasCombined)
+          if (wasCombined) {
             stringIndex = dart.notNull(stringIndex) + 1;
+          }
         } else {
           let rune = codeUnit;
           if (dart.notNull(rune) <= dart.notNull(_TWO_BYTE_LIMIT)) {
             if (dart.notNull(this[_bufferIndex]) + 1 >= dart.notNull(this[_buffer][core.$length]))
               break;
-            this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 192 | dart.notNull(rune) >> 6);
-            this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
+            this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 192 | dart.notNull(rune) >> 6);
+            this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(rune) & 63);
           } else {
             dart.assert(dart.notNull(rune) <= dart.notNull(_THREE_BYTE_LIMIT));
             if (dart.notNull(this[_bufferIndex]) + 2 >= dart.notNull(this[_buffer][core.$length]))
               break;
-            this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 224 | dart.notNull(rune) >> 12);
-            this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) >> 6 & 63);
-            this[_buffer][core.$set](((x$) => this[_bufferIndex] = dart.notNull(x$) + 1, x$).bind(this)(this[_bufferIndex]), 128 | dart.notNull(rune) & 63);
+            this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 224 | dart.notNull(rune) >> 12);
+            this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(rune) >> 6 & 63);
+            this[_buffer][core.$set](((x$) => (x$ = this[_bufferIndex], this[_bufferIndex] = dart.notNull(x$) + 1, x$)).bind(this)(), 128 | dart.notNull(rune) & 63);
           }
         }
       }
       return stringIndex;
     }
   }
   dart.defineNamedConstructor(_Utf8Encoder, 'withBufferSize');
   _Utf8Encoder._DEFAULT_BYTE_BUFFER_SIZE = 1024;
   class _Utf8EncoderSink extends dart.mixin(_Utf8Encoder, StringConversionSinkMixin) {
     _Utf8EncoderSink(sink$) {
@@ skipping 14 matching lines @@
       }
       if (this[_carry] != 0) {
         let nextCodeUnit = 0;
         if (start != end) {
           nextCodeUnit = str.codeUnitAt(start);
         } else {
           dart.assert(isLast);
         }
         let wasCombined = this[_writeSurrogate](this[_carry], nextCodeUnit);
         dart.assert(!dart.notNull(wasCombined) || start != end);
-        if (wasCombined)
+        if (wasCombined) {
           start = dart.notNull(start) + 1;
+        }
         this[_carry] = 0;
       }
       do {
         start = this[_fillBuffer](str, start, end);
         let isLastSlice = dart.notNull(isLast) && start == end;
         if (start == dart.notNull(end) - 1 && dart.notNull(_isLeadSurrogate(str.codeUnitAt(start)))) {
           if (dart.notNull(isLast) && dart.notNull(this[_bufferIndex]) < dart.notNull(this[_buffer][core.$length]) - 3) {
             let hasBeenCombined = this[_writeSurrogate](str.codeUnitAt(start), 0);
             dart.assert(!dart.notNull(hasBeenCombined));
           } else {
@@ skipping 165 matching lines @@
               if (!dart.notNull(this[_isFirstCharacter]) || value != UNICODE_BOM_CHARACTER_RUNE) {
                 this[_stringSink].writeCharCode(value);
               }
               this[_isFirstCharacter] = false;
             }
           while (dart.notNull(i) < dart.notNull(endIndex)) {
             let oneBytes = scanOneByteCharacters(codeUnits, i);
             if (dart.notNull(oneBytes) > 0) {
               this[_isFirstCharacter] = false;
               addSingleBytes(i, dart.notNull(i) + dart.notNull(oneBytes));
-              i = oneBytes;
+              i = dart.notNull(i) + dart.notNull(oneBytes);
               if (i == endIndex)
                 break;
             }
-            let unit = codeUnits[core.$get](((x$) => i = dart.notNull(x$) + 1, x$)(i));
+            let unit = codeUnits[core.$get](((x$) => (x$ = i, i = dart.notNull(x$) + 1, x$))());
             if (dart.notNull(unit) < 0) {
               if (!dart.notNull(this[_allowMalformed])) {
                 throw new core.FormatException(`Negative UTF-8 code unit: -0x${(-dart.notNull(unit)).toRadixString(16)}`);
               }
               this[_stringSink].writeCharCode(UNICODE_REPLACEMENT_CHARACTER_RUNE);
             } else {
               dart.assert(dart.notNull(unit) > dart.notNull(_ONE_BYTE_LIMIT));
               if ((dart.notNull(unit) & 224) == 192) {
                 value = dart.notNull(unit) & 31;
                 expectedUnits = extraUnits = 1;
@@ skipping 331 matching lines @@
   exports.LineSplitter = LineSplitter;
   exports.StringConversionSink = StringConversionSink;
   exports.ClosableStringSink = ClosableStringSink;
   exports.UNICODE_REPLACEMENT_CHARACTER_RUNE = UNICODE_REPLACEMENT_CHARACTER_RUNE;
   exports.UNICODE_BOM_CHARACTER_RUNE = UNICODE_BOM_CHARACTER_RUNE;
   exports.UTF8 = UTF8;
   exports.Utf8Codec = Utf8Codec;
   exports.Utf8Encoder = Utf8Encoder;
   exports.Utf8Decoder = Utf8Decoder;
 })(convert || (convert = {}));