Debugger: add ability to set script source from within OnBeforeCompile.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 1d86382c8fb8f2c8db3aa9d74e70b3a98705b4bb..f45065e004af072313df9e6bf8686d3e62edcfec 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4978,6 +4978,12 @@ class Script: public Struct {
     COMPILATION_TYPE_EVAL = 1
   };
 
+  // Script compilation state.
+  enum CompilationState {
+    COMPILATION_STATE_INITIAL = 0,
+    COMPILATION_STATE_COMPILED = 1
+  };
+
   // [source]: the script source.
   DECL_ACCESSORS(source, Object)
 
@@ -5009,6 +5015,9 @@ class Script: public Struct {
   // [compilation]: how the the script was compiled.
   DECL_ACCESSORS(compilation_type, Smi)
 
+  // [is_compiled]: determines whether the script has already been compiled.
+  DECL_ACCESSORS(compilation_state, Smi)
+
   // [line_ends]: FixedArray of line ends positions.
   DECL_ACCESSORS(line_ends, Object)
 
@@ -5045,7 +5054,9 @@ class Script: public Struct {
   static const int kWrapperOffset = kContextOffset + kPointerSize;
   static const int kTypeOffset = kWrapperOffset + kPointerSize;
   static const int kCompilationTypeOffset = kTypeOffset + kPointerSize;
-  static const int kLineEndsOffset = kCompilationTypeOffset + kPointerSize;
+  static const int kCompilationStateOffset =
+      kCompilationTypeOffset + kPointerSize;
+  static const int kLineEndsOffset = kCompilationStateOffset + kPointerSize;
   static const int kIdOffset = kLineEndsOffset + kPointerSize;
   static const int kEvalFromSharedOffset = kIdOffset + kPointerSize;
   static const int kEvalFrominstructionsOffsetOffset =