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

lib/runtime/dart/core.js

Index: lib/runtime/dart/core.js
diff --git a/lib/runtime/dart/core.js b/lib/runtime/dart/core.js
index 05f795c2d76c200122aef435a712efd157f63a88..d0034f2b29a53d9801fb9ce6dd6501ce1ed6231a 100644
--- a/lib/runtime/dart/core.js
+++ b/lib/runtime/dart/core.js
@@ -177,16 +177,17 @@ var core;
             let sign = match.get(9) == '-' ? -1 : 1;
             let hourDifference = int.parse(match.get(10));
             let minuteDifference = parseIntOrZero(match.get(11));
-            minuteDifference = 60 * dart.notNull(hourDifference);
-            minute = dart.notNull(sign) * dart.notNull(minuteDifference);
+            minuteDifference = dart.notNull(minuteDifference) + 60 * dart.notNull(hourDifference);
+            minute = dart.notNull(minute) - dart.notNull(sign) * dart.notNull(minuteDifference);
           }
         }
         let millisecondsSinceEpoch = DateTime[_brokenDownDateToMillisecondsSinceEpoch](years, month, day, hour, minute, second, millisecond, isUtc);
         if (millisecondsSinceEpoch == null) {
           throw new FormatException("Time out of range", formattedString);
         }
-        if (addOneMillisecond)
+        if (addOneMillisecond) {
           millisecondsSinceEpoch = dart.notNull(millisecondsSinceEpoch) + 1;
+        }
         return new DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch, {isUtc: isUtc});
       } else {
         throw new FormatException("Invalid date format", formattedString);
@@ -941,7 +942,7 @@ var core;
       let offset = this.offset;
       if (!(typeof this.source == 'string')) {
         if (offset != -1) {
-          report = ` (at offset ${offset})`;
+          report = String['+'](report, ` (at offset ${offset})`);
         }
         return report;
       }
@@ -973,9 +974,9 @@ var core;
         }
       }
       if (dart.notNull(lineNum) > 1) {
-        report = ` (at line ${lineNum}, character ${dart.notNull(offset) - dart.notNull(lineStart) + 1})\n`;
+        report = String['+'](report, ` (at line ${lineNum}, character ${dart.notNull(offset) - dart.notNull(lineStart) + 1})\n`);
       } else {
-        report = ` (at character ${dart.notNull(offset) + 1})\n`;
+        report = String['+'](report, ` (at character ${dart.notNull(offset) + 1})\n`);
       }
       let lineEnd = dart.as(dart.dload(this.source, 'length'), int);
       for (let i = offset; i['<'](dart.dload(this.source, 'length')); i = dart.notNull(i) + 1) {
@@ -1047,7 +1048,7 @@ var core;
       [_getKey]() {
         let key = dart.as(_js_helper.Primitives.getProperty(this, Expando[_KEY_PROPERTY_NAME]), String);
         if (key == null) {
-          key = `expando$key$${((x) => Expando[_keyCount] = dart.notNull(x) + 1, x)(Expando[_keyCount])}`;
+          key = `expando$key$${((x) => (x = Expando[_keyCount], Expando[_keyCount] = dart.notNull(x) + 1, x))()}`;
           _js_helper.Primitives.setProperty(this, Expando[_KEY_PROPERTY_NAME], key);
         }
         return key;
@@ -1243,10 +1244,8 @@ var core;
         let growable = opts && 'growable' in opts ? opts.growable : true;
         let result = null;
         if (growable) {
-          result = ((_$) => {
-            _$[exports.$length] = length;
-            return _$;
-          })(new List$(E).from([]));
+          result = new List$(E).from([]);
+          result[exports.$length] = length;
         } else {
           result = new (List$(E))(length);
         }
@@ -2251,7 +2250,7 @@ var core;
         if (char == Uri[_PERCENT]) {
           let replacement = Uri[_normalizeEscape](host, index, true);
           if (dart.notNull(replacement == null) && dart.notNull(isNormalized)) {
-            index = 3;
+            index = dart.notNull(index) + 3;
             continue;
           }
           if (buffer == null)
@@ -2268,7 +2267,7 @@ var core;
             sourceLength = 1;
           }
           buffer.write(replacement);
-          index = sourceLength;
+          index = dart.notNull(index) + dart.notNull(sourceLength);
           sectionStart = index;
           isNormalized = true;
         } else if (Uri[_isRegNameChar](char)) {
@@ -2300,7 +2299,7 @@ var core;
             slice = slice.toLowerCase();
           buffer.write(slice);
           buffer.write(Uri[_escapeChar](char));
-          index = sourceLength;
+          index = dart.notNull(index) + dart.notNull(sourceLength);
           sectionStart = index;
         }
       }
@@ -2395,14 +2394,14 @@ var core;
     static [_isHexDigit](char) {
       if (dart.notNull(Uri[_NINE]) >= dart.notNull(char))
         return dart.notNull(Uri[_ZERO]) <= dart.notNull(char);
-      char = 32;
+      char = dart.notNull(char) | 32;
       return dart.notNull(Uri[_LOWER_CASE_A]) <= dart.notNull(char) && dart.notNull(Uri[_LOWER_CASE_F]) >= dart.notNull(char);
     }
     static [_hexValue](char) {
       dart.assert(Uri[_isHexDigit](char));
       if (dart.notNull(Uri[_NINE]) >= dart.notNull(char))
         return dart.notNull(char) - dart.notNull(Uri[_ZERO]);
-      char = 32;
+      char = dart.notNull(char) | 32;
       return dart.notNull(char) - (dart.notNull(Uri[_LOWER_CASE_A]) - 10);
     }
     static [_normalizeEscape](source, index, lowerCase) {
@@ -2418,7 +2417,7 @@ var core;
       let value = dart.notNull(Uri[_hexValue](firstDigit)) * 16 + dart.notNull(Uri[_hexValue](secondDigit));
       if (Uri[_isUnreservedChar](value)) {
         if (dart.notNull(lowerCase) && dart.notNull(Uri[_UPPER_CASE_A]) <= dart.notNull(value) && dart.notNull(Uri[_UPPER_CASE_Z]) >= dart.notNull(value)) {
-          value = 32;
+          value = dart.notNull(value) | 32;
         }
         return new String.fromCharCode(value);
       }
@@ -2457,7 +2456,7 @@ var core;
           codeUnits[exports.$set](index, Uri[_PERCENT]);
           codeUnits[exports.$set](dart.notNull(index) + 1, hexDigits.codeUnitAt(dart.notNull(byte) >> 4));
           codeUnits[exports.$set](dart.notNull(index) + 2, hexDigits.codeUnitAt(dart.notNull(byte) & 15));
-          index = 3;
+          index = dart.notNull(index) + 3;
           flag = 128;
         }
       }
@@ -2477,7 +2476,7 @@ var core;
           if (char == Uri[_PERCENT]) {
             replacement = Uri[_normalizeEscape](component, index, false);
             if (replacement == null) {
-              index = 3;
+              index = dart.notNull(index) + 3;
               continue;
             }
             if ("%" == replacement) {
@@ -2505,7 +2504,7 @@ var core;
             buffer = new StringBuffer();
           buffer.write(component.substring(sectionStart, index));
           buffer.write(replacement);
-          index = sourceLength;
+          index = dart.notNull(index) + dart.notNull(sourceLength);
           sectionStart = index;
         }
       }
@@ -2532,7 +2531,7 @@ var core;
       let backCount = 0;
       let refStart = 0;
       while (reference.startsWith("../", refStart)) {
-        refStart = 3;
+        refStart = dart.notNull(refStart) + 3;
         backCount = dart.notNull(backCount) + 1;
       }
       let baseEnd = base.lastIndexOf('/');
@@ -2898,12 +2897,12 @@ var core;
           for (let j = 0; dart.notNull(j) < dart.notNull(wildCardLength); j = dart.notNull(j) + 1) {
             bytes[exports.$set](index, 0);
             bytes[exports.$set](dart.notNull(index) + 1, 0);
-            index = 2;
+            index = dart.notNull(index) + 2;
           }
         } else {
           bytes[exports.$set](index, dart.notNull(value) >> 8);
           bytes[exports.$set](dart.notNull(index) + 1, dart.notNull(value) & 255);
-          index = 2;
+          index = dart.notNull(index) + 2;
         }
       }
       return dart.as(bytes, List$(int));
@@ -2939,7 +2938,7 @@ var core;
         if (48 <= dart.notNull(charCode) && dart.notNull(charCode) <= 57) {
           byte = dart.notNull(byte) * 16 + dart.notNull(charCode) - 48;
         } else {
-          charCode = 32;
+          charCode = dart.notNull(charCode) | 32;
           if (97 <= dart.notNull(charCode) && dart.notNull(charCode) <= 102) {
             byte = dart.notNull(byte) * 16 + dart.notNull(charCode) - 87;
           } else {
@@ -2976,7 +2975,7 @@ var core;
               throw new ArgumentError('Truncated URI');
             }
             bytes[exports.$add](Uri[_hexCharPairToByte](text, dart.notNull(i) + 1));
-            i = 2;
+            i = dart.notNull(i) + 2;
           } else if (dart.notNull(plusToSpace) && codeUnit == Uri[_PLUS]) {
             bytes[exports.$add](Uri[_SPACE]);
           } else {