Implement a watchdog timer for scripts that take too long to execute (bug 5837, r=fyren).

--HG--
extra : rebase_source : ffacb38457eca581660ce8f15c444ad828b7fedd

public/jit/assembler.h

@@ -64,6 +64,11 @@ class Assembler
     return pos_ - buffer_;
   }
 
+  // Current offset into the code stream.
+  uint32_t pc() const {
+    return uint32_t(pos_ - buffer_);
+  }
+
  protected:
   void writeByte(uint8_t byte) {
     write<uint8_t>(byte);
@@ -125,11 +130,6 @@ class Assembler
     return int32_t(pos_ - buffer_);
   }
 
-  // pc is the unsigned version of position().
-  uint32_t pc() const {
-    return uint32_t(pos_ - buffer_);
-  }
-
  protected:
   void assertCanWrite(size_t bytes) {
     assert(pos_ + bytes <= end_);

public/jit/x86/assembler-x86.h

@@ -640,6 +640,10 @@ class AssemblerX86 : public Assembler
       emit2(0xdc, 0xc0 + src.code);
   }
 
+  void jmp32(Label *dest) {
+    emit1(0xe9);
+    emitJumpTarget(dest);
+  }
   void jmp(Label *dest) {
     int8_t d8;
     if (canEmitSmallJump(dest, &d8)) {
@@ -655,6 +659,10 @@ class AssemblerX86 : public Assembler
   void jmp(const Operand &target) {
     emit1(0xff, 4, target);
   }
+  void j32(ConditionCode cc, Label *dest) {
+    emit2(0x0f, 0x80 + uint8_t(cc));
+    emitJumpTarget(dest);
+  }
   void j(ConditionCode cc, Label *dest) {
     int8_t d8;
     if (canEmitSmallJump(dest, &d8)) {